diff --git a/Makefile b/Makefile index 8460e80..8efa2eb 100644 --- a/Makefile +++ b/Makefile @@ -4,7 +4,7 @@ # == CHANGE THE SETTINGS BELOW TO SUIT YOUR ENVIRONMENT ======================= # Your platform. See PLATS for possible values. -PLAT= none +PLAT= guess # Where to install. The installation starts in the src and doc directories, # so take care if INSTALL_TOP is not an absolute path. See the local target. @@ -36,7 +36,7 @@ RM= rm -f # == END OF USER SETTINGS -- NO NEED TO CHANGE ANYTHING BELOW THIS LINE ======= # Convenience platforms targets. -PLATS= aix bsd c89 freebsd generic guess linux linux-readline macosx mingw posix solaris +PLATS= guess aix bsd c89 freebsd generic ios linux linux-readline macosx mingw posix solaris # What to install. TO_BIN= lua luac @@ -46,16 +46,13 @@ TO_MAN= lua.1 luac.1 # Lua version and release. V= 5.4 -R= $V.0 +R= $V.6 # Targets start here. all: $(PLAT) -$(PLATS) clean: - cd src && $(MAKE) $@ - -test: dummy - src/lua -v +$(PLATS) help test clean: + @cd src && $(MAKE) $@ install: dummy cd src && $(MKDIR) $(INSTALL_BIN) $(INSTALL_INC) $(INSTALL_LIB) $(INSTALL_MAN) $(INSTALL_LMOD) $(INSTALL_CMOD) @@ -73,15 +70,10 @@ uninstall: local: $(MAKE) install INSTALL_TOP=../install -none: - @echo "Please do 'make PLATFORM' where PLATFORM is one of these:" - @echo " $(PLATS)" - @echo "See doc/readme.html for complete instructions." - -# make may get confused with test/ and install/ +# make may get confused with install/ if it does not support .PHONY. dummy: -# echo config parameters +# Echo config parameters. echo: @cd src && $(MAKE) -s echo @echo "PLAT= $(PLAT)" @@ -101,14 +93,14 @@ echo: @echo "INSTALL_EXEC= $(INSTALL_EXEC)" @echo "INSTALL_DATA= $(INSTALL_DATA)" -# echo pkg-config data +# Echo pkg-config data. pc: @echo "version=$R" @echo "prefix=$(INSTALL_TOP)" @echo "libdir=$(INSTALL_LIB)" @echo "includedir=$(INSTALL_INC)" -# list targets that do not create files (but not all makes understand .PHONY) -.PHONY: all $(PLATS) clean test install uninstall local none dummy echo pc +# Targets that do not create files (not all makes understand .PHONY). +.PHONY: all $(PLATS) help test clean install uninstall local dummy echo pc # (end of Makefile) diff --git a/doc/contents.html b/doc/contents.html index a4e7751..1231e6d 100644 --- a/doc/contents.html +++ b/doc/contents.html @@ -32,7 +32,7 @@

-Copyright © 2019 Lua.org, PUC-Rio. +Copyright © 2020–2023 Lua.org, PUC-Rio. Freely available under the terms of the Lua license. @@ -85,6 +85,8 @@

Contents

  • 3.4.9 – Table Constructors
  • 3.4.10 – Function Calls
  • 3.4.11 – Function Definitions +
  • 3.4.12 – Lists of expressions, multiple results, and adjustment +
  • 3.5 – Visibility Rules @@ -92,14 +94,20 @@

    Contents

  • 4 – The Application Program Interface

  • 5 – The Auxiliary Library @@ -192,7 +200,6 @@

    Lua functions

    debug.getregistry
    debug.getupvalue
    debug.getuservalue
    -debug.setcstacklimit
    debug.sethook
    debug.setlocal
    debug.setmetatable
    @@ -391,6 +398,7 @@

    C API

    lua_callk
    lua_checkstack
    lua_close
    +lua_closeslot
    lua_compare
    lua_concat
    lua_copy
    @@ -470,7 +478,6 @@

    C API

    lua_resume
    lua_rotate
    lua_setallocf
    -lua_setcstacklimit
    lua_setfield
    lua_setglobal
    lua_sethook
    @@ -529,6 +536,7 @@

    auxiliary library

    luaL_buffinit
    luaL_buffinitsize
    luaL_bufflen
    +luaL_buffsub
    luaL_callmeta
    luaL_checkany
    luaL_checkinteger
    @@ -567,6 +575,7 @@

    auxiliary library

    luaL_optstring
    luaL_prepbuffer
    luaL_prepbuffsize
    +luaL_pushfail
    luaL_pushresult
    luaL_pushresultsize
    luaL_ref
    @@ -606,7 +615,7 @@

    constants

    LUA_HOOKLINE
    LUA_HOOKRET
    LUA_HOOKTAILCALL
    -LUAL_BUFFERSIZE
    +LUA_LOADED_TABLE
    LUA_MASKCALL
    LUA_MASKCOUNT
    LUA_MASKLINE
    @@ -634,6 +643,7 @@

    constants

    LUA_OPSHR
    LUA_OPSUB
    LUA_OPUNM
    +LUA_PRELOAD_TABLE
    LUA_REFNIL
    LUA_REGISTRYINDEX
    LUA_RIDX_GLOBALS
    @@ -650,6 +660,7 @@

    constants

    LUA_TUSERDATA
    LUA_USE_APICHECK
    LUA_YIELD
    +LUAL_BUFFERSIZE
    @@ -657,10 +668,10 @@

    constants

    Last update: -Thu Oct 3 17:35:42 UTC 2019 +Sat Apr 1 17:57:05 UTC 2023

    diff --git a/doc/lua.1 b/doc/lua.1 index d728d0b..3f472fd 100644 --- a/doc/lua.1 +++ b/doc/lua.1 @@ -1,5 +1,5 @@ -.\" $Id: lua.man,v 1.14 2016/10/17 15:43:50 lhf Exp $ -.TH LUA 1 "$Date: 2016/10/17 15:43:50 $" +.\" $Id: lua.man,v 1.14 2022/09/23 09:06:36 lhf Exp $ +.TH LUA 1 "$Date: 2022/09/23 09:06:36 $" .SH NAME lua \- Lua interpreter .SH SYNOPSIS @@ -25,52 +25,57 @@ the Lua compiler.) .B lua can be used as a batch interpreter and also interactively. .LP -The given -.I options -are handled in order and then +After handling the +.IR options , the Lua program in file .I script is loaded and executed. -The given +The .I args are available to .I script as strings in a global table named -.BR arg . -If no options or arguments are given, -then -.B "\-v \-i" -is assumed when the standard input is a terminal; -otherwise, -.B "\-" -is assumed. +.B arg +and also as arguments to its main function. +When called without arguments, +.B lua +behaves as +.B "lua \-v \-i" +if the standard input is a terminal, +and as +.B "lua \-" +otherwise. .LP In interactive mode, .B lua prompts the user, reads lines from the standard input, and executes them as they are read. -If the line contains an expression or list of expressions, -then the line is evaluated and the results are printed. +If the line contains an expression, +then the line is evaluated and the result is printed. If a line does not contain a complete statement, then a secondary prompt is displayed and lines are read until a complete statement is formed or a syntax error is found. .LP -At the very start, -before even handling the command line, +Before handling command line options and scripts, .B lua checks the contents of the environment variables -.B LUA_INIT_5_3 -or +.B LUA_INIT_5_4 +and .BR LUA_INIT , in that order. -If the contents is of the form +If the contents are of the form .RI '@ filename ', then .I filename is executed. -Otherwise, the string is assumed to be a Lua statement and is executed. +Otherwise, the contents are assumed to be a Lua statement and is executed. +When +.B LUA_INIT_5_4 +is defined, +.B LUA_INIT +is ignored. .SH OPTIONS .TP .BI \-e " stat" @@ -81,11 +86,17 @@ execute statement enter interactive mode after executing .IR script . .TP -.BI \-l " name" -execute the equivalent of -.IB name =require(' name ') -before executing -.IR script . +.BI \-l " mod" +require library +.I mod +into global +.IR mod . +.TP +.BI \-l " g=mod" +require library +.I mod +into global +.IR g . .TP .B \-v show version information. @@ -93,18 +104,50 @@ show version information. .B \-E ignore environment variables. .TP +.B \-W +turn warnings on. +.TP .B \-\- stop handling options. .TP .B \- stop handling options and execute the standard input as a file. +.SH ENVIRONMENT VARIABLES +The following environment variables affect the execution of +.BR lua . +When defined, +the version-specific variants take priority +and the version-neutral variants are ignored. +.TP +.B LUA_INIT, LUA_INIT_5_4 +Code to be executed before command line options and scripts. +.TP +.B LUA_PATH, LUA_PATH_5_4 +Initial value of package.cpath, +the path used by require to search for Lua loaders. +.TP +.B LUA_CPATH, LUA_CPATH_5_4 +Initial value of package.cpath, +the path used by require to search for C loaders. +.SH EXIT STATUS +If a script calls os.exit, +then +.B lua +exits with the given exit status. +Otherwise, +.B lua +exits +with EXIT_SUCCESS (0 on POSIX systems) if there were no errors +and +with EXIT_FAILURE (1 on POSIX systems) if there were errors. +Errors raised in interactive mode do not cause exits. +.SH DIAGNOSTICS +Error messages should be self explanatory. .SH "SEE ALSO" .BR luac (1) .br The documentation at lua.org, especially section 7 of the reference manual. -.SH DIAGNOSTICS -Error messages should be self explanatory. .SH AUTHORS R. Ierusalimschy, L. H. de Figueiredo, diff --git a/doc/manual.html b/doc/manual.html index 5a6641c..0af688b 100644 --- a/doc/manual.html +++ b/doc/manual.html @@ -19,7 +19,7 @@

    -Copyright © 2019 Lua.org, PUC-Rio. +Copyright © 2020–2023 Lua.org, PUC-Rio. Freely available under the terms of the Lua license. @@ -63,7 +63,7 @@

    1 – Introduction

    Lua is implemented as a library, written in clean C, -the common subset of Standard C and C++. +the common subset of standard C and C++. The Lua distribution includes a host program called lua, which uses the Lua library to offer a complete, standalone Lua interpreter, @@ -106,11 +106,15 @@

    1 – Introduction

    2 – Basic Concepts

    + +

    This section describes the basic concepts of the language. + +

    2.1 – Values and Types

    @@ -137,7 +141,13 @@

    2.1 – Values and Types

    it often represents the absence of a useful value. The type boolean has two values, false and true. Both nil and false make a condition false; -any other value makes it true. +they are collectively called false values. +Any other value makes a condition true. +Despite its name, +false is frequently used as an alternative to nil, +with the key difference that false behaves +like a regular value in a table, +while a nil in a table represents an absent key.

    @@ -153,6 +163,16 @@

    2.1 – Values and Types

    (See macro LUA_32BITS in file luaconf.h.) +

    +Unless stated otherwise, +any overflow when manipulating integer values wrap around, +according to the usual rules of two-complement arithmetic. +(In other words, +the actual result is the unique representable integer +that is equal modulo 2n to the mathematical result, +where n is the number of bits of the integer type.) + +

    Lua has explicit rules about when each subtype is used, but it also converts between them automatically as needed (see §3.4.3). @@ -304,7 +324,7 @@

    2.2 – Environments and the Global Environment

    Lua keeps a distinguished environment called the global environment. -This value is kept at a special index in the C registry (see §4.5). +This value is kept at a special index in the C registry (see §4.3). In Lua, the global variable _G is initialized with this same value. (_G is never used internally, so changing its value will affect only your own code.) @@ -330,39 +350,57 @@

    2.2 – Environments and the Global Environment

    2.3 – Error Handling

    +

    +Several operations in Lua can raise an error. +An error interrupts the normal flow of the program, +which can continue by catching the error. + + +

    +Lua code can explicitly raise an error by calling the +error function. +(This function never returns.) + + +

    +To catch errors in Lua, +you can do a protected call, +using pcall (or xpcall). +The function pcall calls a given function in protected mode. +Any error while running the function stops its execution, +and control returns immediately to pcall, +which returns a status code. + +

    Because Lua is an embedded extension language, -all Lua actions start from C code in the host program -calling a function from the Lua library. +Lua code starts running by a call +from C code in the host program. (When you use Lua standalone, the lua application is the host program.) -Whenever an error occurs during +Usually, this call is protected; +so, when an otherwise unprotected error occurs during the compilation or execution of a Lua chunk, control returns to the host, -which can take appropriate measures -(such as printing an error message). - - -

    -Lua code can explicitly generate an error by calling the -error function. -If you need to catch errors in Lua, -you can use pcall or xpcall -to call a given function in protected mode. +which can take appropriate measures, +such as printing an error message.

    Whenever there is an error, -an error object (also called an error message) +an error object is propagated with information about the error. Lua itself only generates errors whose error object is a string, but programs may generate errors with any value as the error object. It is up to the Lua program or its host to handle such error objects. +For historical reasons, +an error object is often called an error message, +even though it does not have to be a string.

    -When you use xpcall or lua_pcall, +When you use xpcall (or lua_pcall, in C) you may give a message handler to be called in case of errors. This function is called with the original error object @@ -375,9 +413,9 @@

    2.3 – Error Handling

    will call the message handler again. If this loop goes on for too long, Lua breaks it and returns an appropriate message. -(The message handler is called only for regular runtime errors. +The message handler is called only for regular runtime errors. It is not called for memory-allocation errors -nor for errors while running finalizers.) +nor for errors while running finalizers or other message handlers.

    @@ -401,7 +439,7 @@

    2.4 – Metatables and Metamethods

    You can change several aspects of the behavior of a value by setting specific fields in its metatable. For instance, when a non-numeric value is the operand of an addition, -Lua checks for a function in the field "__add" of the value's metatable. +Lua checks for a function in the field __add of the value's metatable. If it finds one, Lua calls this function to perform the addition. @@ -409,11 +447,14 @@

    2.4 – Metatables and Metamethods

    The key for each event in a metatable is a string with the event name prefixed by two underscores; -the corresponding values are called metamethods. +the corresponding value is called a metavalue. +For most events, the metavalue must be a function, +which is then called a metamethod. In the previous example, the key is the string "__add" and the metamethod is the function that performs the addition. Unless stated otherwise, -metamethods should be function values. +a metamethod may in fact be any callable value, +which is either a function or a value with a __call metamethod.

    @@ -581,21 +622,21 @@

    2.4 – Metatables and Metamethods

    The indexing access operation table[key]. This event happens when table is not a table or when key is not present in table. -The metamethod is looked up in table. +The metavalue is looked up in the metatable of table.

    -Despite the name, -the metamethod for this event can be either a function or a table. +The metavalue for this event can be either a function, a table, +or any value with an __index metavalue. If it is a function, it is called with table and key as arguments, and the result of the call (adjusted to one value) is the result of the operation. -If it is a table, -the final result is the result of indexing this table with key. +Otherwise, +the final result is the result of indexing this metavalue with key. This indexing is regular, not raw, -and therefore can trigger another metamethod. +and therefore can trigger another __index metavalue.

  • __newindex: @@ -603,22 +644,24 @@

    2.4 – Metatables and Metamethods

    Like the index event, this event happens when table is not a table or when key is not present in table. -The metamethod is looked up in table. +The metavalue is looked up in the metatable of table.

    Like with indexing, -the metamethod for this event can be either a function or a table. +the metavalue for this event can be either a function, a table, +or any value with an __newindex metavalue. If it is a function, it is called with table, key, and value as arguments. -If it is a table, -Lua does an indexing assignment to this table with the same key and value. +Otherwise, +Lua repeats the indexing assignment over this metavalue +with the same key and value. This assignment is regular, not raw, -and therefore can trigger another metamethod. +and therefore can trigger another __newindex metavalue.

    -Whenever there is a __newindex metamethod, +Whenever a __newindex metavalue is invoked, Lua does not perform the primitive assignment. If needed, the metamethod itself can call rawset @@ -649,7 +692,7 @@

    2.4 – Metatables and Metamethods

    and __name. (The entry __name, when it contains a string, -is used by some error-reporting functions to build error messages.) +may be used by tostring and in error messages.)

    @@ -685,18 +728,40 @@

    2.4 – Metatables and Metamethods

    2.5 – Garbage Collection

    + +

    Lua performs automatic memory management. This means that you do not have to worry about allocating memory for new objects or freeing it when the objects are no longer needed. Lua manages memory automatically by running -a garbage collector to collect all dead objects -(that is, objects that are no longer accessible from Lua). +a garbage collector to collect all dead objects. All memory used by Lua is subject to automatic management: strings, tables, userdata, functions, threads, internal structures, etc. +

    +An object is considered dead +as soon as the collector can be sure the object +will not be accessed again in the normal execution of the program. +("Normal execution" here excludes finalizers, +which can resurrect dead objects (see §2.5.3), +and excludes also operations using the debug library.) +Note that the time when the collector can be sure that an object +is dead may not coincide with the programmer's expectations. +The only guarantees are that Lua will not collect an object +that may still be accessed in the normal execution of the program, +and it will eventually collect an object +that is inaccessible from Lua. +(Here, +inaccessible from Lua means that neither a variable nor +another live object refer to the object.) +Because Lua has no knowledge about C code, +it never collects objects accessible through the registry (see §4.3), +which includes the global environment (see §2.2). + +

    The garbage collector (GC) in Lua can work in two modes: incremental and generational. @@ -721,6 +786,8 @@

    2.5 – Garbage Collection

    + +

    2.5.1 – Incremental Garbage Collection

    @@ -786,7 +853,7 @@

    2.5.2 – Generational Garbage Collection

    the collector does frequent minor collections, which traverses only objects recently created. If after a minor collection the use of memory is still above a limit, -the collector does a major collection, +the collector does a stop-the-world major collection, which traverses all objects. The generational mode uses two parameters: the minor multiplier and the the major multiplier. @@ -827,7 +894,7 @@

    2.5.3 – Garbage-Collection Metamethods

    for full userdata (see §2.4). These metamethods, called finalizers, are called when the garbage collector detects that the -corresponding table or userdata is unreachable. +corresponding table or userdata is dead. Finalizers allow you to coordinate Lua's garbage collection with external resource management such as closing files, network or database connections, @@ -839,14 +906,14 @@

    2.5.3 – Garbage-Collection Metamethods

    you must mark it for finalization. You mark an object for finalization when you set its metatable -and the metatable has a field indexed by the string "__gc". +and the metatable has a __gc metamethod. Note that if you set a metatable without a __gc field and later create that field in the metatable, the object will not be marked for finalization.

    -When a marked object becomes unreachable, +When a marked object becomes dead, it is not collected immediately by the garbage collector. Instead, Lua puts it in a list. After the collection, @@ -879,10 +946,10 @@

    2.5.3 – Garbage-Collection Metamethods

    then the resurrection is permanent. Moreover, if the finalizer marks a finalizing object for finalization again, its finalizer will be called again in the next cycle where the -object is unreachable. +object is dead. In any case, the object memory is freed only in a GC cycle where -the object is unreachable and not marked for finalization. +the object is dead and not marked for finalization.

    @@ -894,11 +961,8 @@

    2.5.3 – Garbage-Collection Metamethods

    -Finalizers cannot yield. -Except for that, they can do anything, -such as raise errors, create new objects, -or even run the garbage collector. -However, because they can run in unpredictable times, +Finalizers cannot yield nor run the garbage collector. +Because they can run in unpredictable times, it is good practice to restrict each finalizer to the minimum necessary to properly release its associated resource. @@ -933,7 +997,7 @@

    2.5.4 – Weak Tables

    the whole pair is removed from the table. The weakness of a table is controlled by the __mode field of its metatable. -This field, if present, must be one of the following strings: +This metavalue, if present, must be one of the following strings: "k", for a table with weak keys; "v", for a table with weak values; or "kv", for a table with both weak keys and values. @@ -1120,6 +1184,8 @@

    2.6 – Coroutines

    3 – The Language

    + +

    This section describes the lexis, the syntax, and the semantics of Lua. In other words, @@ -1142,6 +1208,8 @@

    3 – The Language

    + +

    3.1 – Lexical Conventions

    @@ -1149,7 +1217,7 @@

    3.1 – Lexical Conventions

    It ignores spaces and comments between lexical elements (tokens), except as delimiters between two tokens. In source code, -Lua recognizes as spaces the standard ASCII white-space +Lua recognizes as spaces the standard ASCII whitespace characters space, form feed, newline, carriage return, horizontal tab, and vertical tab. @@ -1214,7 +1282,7 @@

    3.1 – Lexical Conventions

    A backslash followed by a line break results in a newline in the string. The escape sequence '\z' skips the following span -of white-space characters, +of whitespace characters, including line breaks; it is particularly useful to break and indent a long literal string into multiple lines without adding the newlines and spaces @@ -1311,7 +1379,9 @@

    3.1 – Lexical Conventions

    which start with 0x or 0X. Hexadecimal constants also accept an optional fractional part plus an optional binary exponent, -marked by a letter 'p' or 'P'. +marked by a letter 'p' or 'P' and written in decimal. +(For instance, 0x1.fp10 denotes 1984, +which is 0x1f / 16 multiplied by 210.)

    @@ -1322,8 +1392,13 @@

    3.1 – Lexical Conventions

    it denotes an integer; otherwise (that is, a decimal integer numeral that overflows), it denotes a float. -(Hexadecimal integer numerals that overflow wrap around; -they always denote an integer value.) +Hexadecimal numerals with neither a radix point nor an exponent +always denote an integer value; +if the value overflows, it wraps around +to fit into a valid integer. + + +

    Examples of valid integer constants are 

    @@ -1410,6 +1485,8 @@ 
    3.2 – Variables
    
 
 
    3.3 – Statements
    
 
+
+
 
    
 Lua supports an almost conventional set of statements,
 similar to those in other conventional languages.
@@ -1419,6 +1496,8 @@ 
    3.3 – Statements
    
 
 
 
+
+
 
    3.3.1 – Blocks
    
 
 
    
@@ -1544,20 +1623,14 @@ 
    3.3.3 – Assignment
    
 
    
 Before the assignment,
 the list of values is adjusted to the length of
-the list of variables.
-If there are more values than needed,
-the excess values are thrown away.
-If there are fewer values than needed,
-the list is extended with nil's.
-If the list of expressions ends with a function call,
-then all values returned by that call enter the list of values,
-before the adjustment
-(except when the call is enclosed in parentheses; see §3.4).
+the list of variables (see §3.4.12).
 
 
 
    
-The assignment statement first evaluates all its expressions
-and only then the assignments are performed.
+If a variable is both assigned and read
+inside a multiple assignment,
+Lua ensures that all reads get the value of the variable
+before the assignment.
 Thus the code
 
 
    @@ -1581,6 +1654,14 @@ 
    3.3.3 – Assignment
    
 cyclically permutes the values of x, y, and z.
 
 
+
    
+Note that this guarantee covers only accesses
+syntactically inside the assignment statement.
+If a function or a metamethod called during the assignment
+changes the value of a variable,
+Lua gives no guarantees about the order of that access.
+
+
 
    
 An assignment to a global name x = val
 is equivalent to the assignment
@@ -1651,11 +1732,6 @@ 
    3.3.4 – Control Structures
    
 even if this other label has been declared in an enclosing block.
 
 
-
    
-Labels and empty statements are called void statements,
-as they perform no actions.
-
-
 
    
 The break statement terminates the execution of a
 while, repeat, or for loop,
@@ -1712,12 +1788,11 @@ 
    The numerical for loop
    
 	stat ::= for Name ‘=’ exp ‘,’ exp [‘,’ exp] do block end
 
    
 The given identifier (Name) defines the control variable,
-which is local to the loop body (block).
+which is a new variable local to the loop body (block).
 
 
 
    
-The loop starts by evaluating once the three control expressions;
-they must all result in numbers.
+The loop starts by evaluating once the three control expressions.
 Their values are called respectively
 the initial value, the limit, and the step.
 If the step is absent, it defaults to 1.
@@ -1727,8 +1802,9 @@ 
    The numerical for loop
    
 If both the initial value and the step are integers,
 the loop is done with integers;
 note that the limit may not be an integer.
-Otherwise, the loop is done with floats.
-(Beware of floating-point accuracy in this case.)
+Otherwise, the three values are converted to
+floats and the loop is done with floats.
+Beware of floating-point accuracy in this case.
 
 
 
    
@@ -1917,16 +1993,8 @@ 
    3.3.8 – To-be-closed Variables
    
 If there is any error while running a closing method,
 that error is handled like an error in the regular code
 where the variable was defined.
-However, Lua may call the method one more time.
-
-
-
    
 After an error,
 the other pending closing methods will still be called.
-Errors in these methods
-interrupt the respective method and generate a warning,
-but are otherwise ignored;
-the error reported is only the original one.
 
 
 
    
@@ -1954,6 +2022,8 @@ 
    3.3.8 – To-be-closed Variables
    
 
 
    3.4 – Expressions
    
 
+
+
 
    
 The basic expressions in Lua are the following:
 
@@ -1978,7 +2048,7 @@ 
    3.4 – Expressions
    
 table constructors are explained in §3.4.9.
 Vararg expressions,
 denoted by three dots ('...'), can only be used when
-directly inside a vararg function;
+directly inside a variadic function;
 they are explained in §3.4.11.
 
 
@@ -1993,50 +2063,6 @@ 
    3.4 – Expressions
    
 and the unary length operator (see §3.4.7).
 
 
-
    
-Both function calls and vararg expressions can result in multiple values.
-If a function call is used as a statement (see §3.3.6),
-then its return list is adjusted to zero elements,
-thus discarding all returned values.
-If an expression is used as the last (or the only) element
-of a list of expressions,
-then no adjustment is made
-(unless the expression is enclosed in parentheses).
-In all other contexts,
-Lua adjusts the result list to one element,
-either discarding all values except the first one
-or adding a single nil if there are no values.
-
-
-
    
-Here are some examples:
-
-
    -     f()                -- adjusted to 0 results
-     g(f(), x)          -- f() is adjusted to 1 result
-     g(x, f())          -- g gets x plus all results from f()
-     a,b,c = f(), x     -- f() is adjusted to 1 result (c gets nil)
-     a,b = ...          -- a gets the first vararg argument, b gets
-                        -- the second (both a and b can get nil if there
-                        -- is no corresponding vararg argument)
-     
-     a,b,c = x, f()     -- f() is adjusted to 2 results
-     a,b,c = f()        -- f() is adjusted to 3 results
-     return f()         -- returns all results from f()
-     return ...         -- returns all received vararg arguments
-     return x,y,f()     -- returns x, y, and all results from f()
-     {f()}              -- creates a list with all results from f()
-     {...}              -- creates a list with all vararg arguments
-     {f(), nil}         -- f() is adjusted to 1 result
-
    
-
-
    
-Any expression enclosed in parentheses always results in only one value.
-Thus,
-(f(x,y,z)) is always a single value,
-even if f returns several values.
-(The value of (f(x,y,z)) is the first value returned by f
-or nil if f does not return any values.)
 
 
 
@@ -2090,12 +2116,7 @@ 
    3.4.1 – Arithmetic Operators
    
 
 
    
 In case of overflows in integer arithmetic,
-all operations wrap around,
-according to the usual rules of two-complement arithmetic.
-(In other words,
-they return the unique representable integer
-that is equal modulo 2n to the mathematical result,
-where n is the number of bits of the integer type.)
+all operations wrap around.
 
 
 
@@ -2164,9 +2185,29 @@ 
    3.4.3 – Coercions and Conversions
    
 
 
    
 Several places in Lua coerce strings to numbers when necessary.
+In particular,
+the string library sets metamethods that try to coerce
+strings to numbers in all arithmetic operations.
+If the conversion fails,
+the library calls the metamethod of the other operand
+(if present) or it raises an error.
+Note that bitwise operators do not do this coercion.
+
+
+
    
+It is always a good practice not to rely on the
+implicit coercions from strings to numbers,
+as they are not always applied;
+in particular, "1"==1 is false and "1"<1 raises an error
+(see §3.4.4).
+These coercions exist mainly for compatibility and may be removed
+in future versions of the language.
+
+
+
    
 A string is converted to an integer or a float
 following its syntax and the rules of the Lua lexer.
-(The string may have also leading and trailing spaces and a sign.)
+The string may have also leading and trailing whitespaces and a sign.
 All conversions from strings to numbers
 accept both a dot and the current locale mark
 as the radix character.
@@ -2174,18 +2215,10 @@ 
    3.4.3 – Coercions and Conversions
    
 If the string is not a valid numeral,
 the conversion fails.
 If necessary, the result of this first step is then converted
-to the required number subtype following the previous rules
+to a specific number subtype following the previous rules
 for conversions between floats and integers.
 
 
-
    
-The string library uses metamethods that try to coerce
-strings to numbers in all arithmetic operations.
-If the conversion fails,
-the library calls the metamethod of the other operand
-(if present) or it raises an error.
-
-
 
    
 The conversion from numbers to strings uses a
 non-specified human-readable format.
@@ -2334,16 +2367,21 @@ 
    3.4.7 – The Length Operator
    
 
    
 The length operator applied on a table
 returns a border in that table.
-A border in a table t is any natural number
+A border in a table t is any non-negative integer
 that satisfies the following condition:
 
 
    -     (border == 0 or t[border] ~= nil) and t[border + 1] == nil
+     (border == 0 or t[border] ~= nil) and
+     (t[border + 1] == nil or border == math.maxinteger)
 
    
 In words,
-a border is any (natural) index present in the table
-that is followed by an absent index
-(or zero, when index 1 is absent).
+a border is any positive integer index present in the table
+that is followed by an absent index,
+plus two limit cases:
+zero, when index 1 is absent;
+and the maximum value for an integer, when that index is present.
+Note that keys that are not positive integers
+do not interfere with borders.
 
 
 
    
@@ -2354,12 +2392,9 @@ 
    3.4.7 – The Length Operator
    
 and therefore it is not a sequence.
 (The nil at index 4 is called a hole.)
 The table {nil, 20, 30, nil, nil, 60, nil}
-has three borders (0, 3, and 6) and three holes
-(at indices 1, 4, and 5),
+has three borders (0, 3, and 6),
 so it is not a sequence, too.
 The table {} is a sequence with border 0.
-Note that non-natural keys do not interfere
-with whether a table is a sequence.
 
 
 
    
@@ -2377,7 +2412,7 @@ 
    3.4.7 – The Length Operator
    
 
    
 The computation of the length of a table
 has a guaranteed worst time of O(log n),
-where n is the largest natural key in the table.
+where n is the largest integer key in the table.
 
 
 
    
@@ -2467,9 +2502,9 @@ 
    3.4.9 – Table Constructors
    
 
 
    
 If the last field in the list has the form exp
-and the expression is a function call or a vararg expression,
+and the expression is a multires expression,
 then all values returned by this expression enter the list consecutively
-(see §3.4.10).
+(see §3.4.12).
 
 
 
    
@@ -2533,7 +2568,7 @@ 
    3.4.10 – Function Calls
    
 scope of a to-be-closed variable is called a tail call.
 Lua implements proper tail calls
 (or proper tail recursion):
-in a tail call,
+In a tail call,
 the called function reuses the stack entry of the calling function.
 Therefore, there is no limit on the number of nested tail calls that
 a program can execute.
@@ -2636,22 +2671,16 @@ 
    3.4.11 – Function Definitions

    When a Lua function is called, it adjusts its list of arguments to -the length of its list of parameters, -unless the function is a vararg function, +the length of its list of parameters (see §3.4.12), +unless the function is a variadic function, which is indicated by three dots ('...') at the end of its parameter list. -A vararg function does not adjust its argument list; +A variadic function does not adjust its argument list; instead, it collects all extra arguments and supplies them to the function through a vararg expression, which is also written as three dots. The value of this expression is a list of all actual extra arguments, -similar to a function with multiple results. -If a vararg expression is used inside another expression -or in the middle of a list of expressions, -then its return list is adjusted to one element. -If the expression is used as the last element of a list of expressions, -then no adjustment is made -(unless that last expression is enclosed in parentheses). +similar to a function with multiple results (see §3.4.12).

    @@ -2666,7 +2695,7 @@

    3.4.11 – Function Definitions

    to the vararg expression: 
    -     CALL            PARAMETERS
+     CALL             PARAMETERS
      
      f(3)             a=3, b=nil
      f(3, 4)          a=3, b=4
@@ -2712,6 +2741,122 @@ 
    3.4.11 – Function Definitions
    
 
 
 
+
    3.4.12 – Lists of expressions, multiple results,
+and adjustment
    
+
+
    
+Both function calls and vararg expressions can result in multiple values.
+These expressions are called multires expressions.
+
+
+
    
+When a multires expression is used as the last element
+of a list of expressions,
+all results from the expression are added to the
+list of values produced by the list of expressions.
+Note that a single expression
+in a place that expects a list of expressions
+is the last expression in that (singleton) list.
+
+
+
    
+These are the places where Lua expects a list of expressions:
+
+
    
+In the last four cases,
+the list of values from the list of expressions
+must be adjusted to a specific length:
+the number of parameters in a call to a non-variadic function
+(see §3.4.11),
+the number of variables in a multiple assignment or
+a local declaration,
+and exactly four values for a generic for loop.
+The adjustment follows these rules:
+If there are more values than needed,
+the extra values are thrown away;
+if there are fewer values than needed,
+the list is extended with nil's.
+When the list of expressions ends with a multires expression,
+all results from that expression enter the list of values
+before the adjustment.
+
+
+
    
+When a multires expression is used
+in a list of expressions without being the last element,
+or in a place where the syntax expects a single expression,
+Lua adjusts the result list of that expression to one element.
+As a particular case,
+the syntax expects a single expression inside a parenthesized expression;
+therefore, adding parentheses around a multires expression
+forces it to produce exactly one result.
+
+
+
    
+We seldom need to use a vararg expression in a place
+where the syntax expects a single expression.
+(Usually it is simpler to add a regular parameter before
+the variadic part and use that parameter.)
+When there is such a need,
+we recommend assigning the vararg expression
+to a single variable and using that variable
+in its place.
+
+
+
    
+Here are some examples of uses of mutlres expressions.
+In all cases, when the construction needs
+"the n-th result" and there is no such result,
+it uses a nil.
+
+
    +     print(x, f())      -- prints x and all results from f().
+     print(x, (f()))    -- prints x and the first result from f().
+     print(f(), x)      -- prints the first result from f() and x.
+     print(1 + f())     -- prints 1 added to the first result from f().
+     local x = ...      -- x gets the first vararg argument.
+     x,y = ...          -- x gets the first vararg argument,
+                        -- y gets the second vararg argument.
+     x,y,z = w, f()     -- x gets w, y gets the first result from f(),
+                        -- z gets the second result from f().
+     x,y,z = f()        -- x gets the first result from f(),
+                        -- y gets the second result from f(),
+                        -- z gets the third result from f().
+     x,y,z = f(), g()   -- x gets the first result from f(),
+                        -- y gets the first result from g(),
+                        -- z gets the second result from g().
+     x,y,z = (f())      -- x gets the first result from f(), y and z get nil.
+     return f()         -- returns all results from f().
+     return x, ...      -- returns x and all received vararg arguments.
+     return x,y,f()     -- returns x, y, and all results from f().
+     {f()}              -- creates a list with all results from f().
+     {...}              -- creates a list with all vararg arguments.
+     {f(), 5}           -- creates a list with the first result from f() and 5.
+
    
+
+
+
+
 
 
 
    3.5 – Visibility Rules
    
@@ -2722,6 +2867,7 @@ 
    3.5 – Visibility Rules
    
 The scope of a local variable begins at the first statement after
 its declaration and lasts until the last non-void statement
 of the innermost block that includes the declaration.
+(Void statements are labels and empty statements.)
 Consider the following example:
 
 
    @@ -2778,6 +2924,8 @@ 
    3.5 – Visibility Rules
    
 
 
    4 – The Application Program Interface
    
 
+
+
 
    
 
 This section describes the C API for Lua, that is,
@@ -2827,8 +2975,12 @@ 
    4 – The Application Program Interface
    
 
 
 
+
+
 
    4.1 – The Stack
    
 
+
+
 
    
 Lua uses a virtual stack to pass values to and from C.
 Each element in this stack represents a Lua value
@@ -2868,39 +3020,44 @@ 
    4.1 – The Stack
    
 
 
 
-
    4.2 – Stack Size
    
+
    4.1.1 – Stack Size
    
 
 
    
 When you interact with the Lua API,
 you are responsible for ensuring consistency.
 In particular,
 you are responsible for controlling stack overflow.
-You can use the function lua_checkstack
-to ensure that the stack has enough space for pushing new elements.
+When you call any API function,
+you must ensure the stack has enough room to accommodate the results.
+
+
+
    
+There is one exception to the above rule:
+When you call a Lua function
+without a fixed number of results (see lua_call),
+Lua ensures that the stack has enough space for all results.
+However, it does not ensure any extra space.
+So, before pushing anything on the stack after such a call
+you should use lua_checkstack.
 
 
 
    
 Whenever Lua calls C,
 it ensures that the stack has space for
-at least LUA_MINSTACK extra slots.
+at least LUA_MINSTACK extra elements;
+that is, you can safely push up to LUA_MINSTACK values into it.
 LUA_MINSTACK is defined as 20,
 so that usually you do not have to worry about stack space
 unless your code has loops pushing elements onto the stack.
-
-
-
    
-When you call a Lua function
-without a fixed number of results (see lua_call),
-Lua ensures that the stack has enough space for all results,
-but it does not ensure any extra space.
-So, before pushing anything in the stack after such a call
-you should use lua_checkstack.
+Whenever necessary,
+you can use the function lua_checkstack
+to ensure that the stack has enough space for pushing new elements.
 
 
 
 
 
-
    4.3 – Valid and Acceptable Indices
    
+
    4.1.2 – Valid and Acceptable Indices
    
 
 
    
 Any function in the API that receives stack indices
@@ -2916,8 +3073,8 @@ 
    4.3 – Valid and Acceptable Indices
    
 plus pseudo-indices,
 which represent some positions that are accessible to C code
 but that are not in the stack.
-Pseudo-indices are used to access the registry (see §4.5)
-and the upvalues of a C function (see §4.4).
+Pseudo-indices are used to access the registry (see §4.3)
+and the upvalues of a C function (see §4.2).
 
 
 
    
@@ -2929,7 +3086,7 @@ 
    4.3 – Valid and Acceptable Indices
    
 within the space allocated for the stack,
 that is, indices up to the stack size.
 (Note that 0 is never an acceptable index.)
-Indices to upvalues (see §4.4) greater than the real number
+Indices to upvalues (see §4.2) greater than the real number
 of upvalues in the current C function are also acceptable (but invalid).
 Except when noted otherwise,
 functions in the API work with acceptable indices.
@@ -2953,7 +3110,52 @@ 
    4.3 – Valid and Acceptable Indices
    
 
 
 
-
    4.4 – C Closures
    
+
    4.1.3 – Pointers to strings
    
+
+
    
+Several functions in the API return pointers (const char*)
+to Lua strings in the stack.
+(See lua_pushfstring, lua_pushlstring,
+lua_pushstring, and lua_tolstring.
+See also luaL_checklstring, luaL_checkstring,
+and luaL_tolstring in the auxiliary library.)
+
+
+
    
+In general,
+Lua's garbage collection can free or move internal memory
+and then invalidate pointers to internal strings.
+To allow a safe use of these pointers,
+the API guarantees that any pointer to a string in a stack index
+is valid while the string value at that index is not removed from the stack.
+(It can be moved to another index, though.)
+When the index is a pseudo-index (referring to an upvalue),
+the pointer is valid while the corresponding call is active and
+the corresponding upvalue is not modified.
+
+
+
    
+Some functions in the debug interface
+also return pointers to strings,
+namely lua_getlocal, lua_getupvalue,
+lua_setlocal, and lua_setupvalue.
+For these functions, the pointer is guaranteed to
+be valid while the caller function is active and
+the given closure (if one was given) is in the stack.
+
+
+
    
+Except for these guarantees,
+the garbage collector is free to invalidate
+any pointer to internal strings.
+
+
+
+
+
+
+
+
    4.2 – C Closures
    
 
 
    
 When a C function is created,
@@ -2987,7 +3189,7 @@ 
    4.4 – C Closures
    
 
 
 
-
    4.5 – Registry
    
+
    4.3 – Registry
    
 
 
    
 Lua provides a registry,
@@ -3036,7 +3238,9 @@ 
    4.5 – Registry
    
 
 
 
-
    4.6 – Error Handling in C
    
+
    4.4 – Error Handling in C
    
+
+
 
 
    
 Internally, Lua uses the C longjmp facility to handle errors.
@@ -3095,13 +3299,48 @@ 
    4.6 – Error Handling in C
    
 in particular, the error object is on the top of the stack.
 However, there is no guarantee about stack space.
 To push anything on the stack,
-the panic function must first check the available space (see §4.2).
+the panic function must first check the available space (see §4.1.1).
 
 
 
 
 
-
    4.7 – Handling Yields in C
    
+
    4.4.1 – Status Codes
    
+
+
    
+Several functions that report errors in the API use the following
+status codes to indicate different kinds of errors or other conditions:
+
+
      
+
+
    • LUA_OK (0):  no errors.
      • 
+
+
    • LUA_ERRRUN:  a runtime error.
      • 
+
+
    • LUA_ERRMEM: 
+memory allocation error.
+For such errors, Lua does not call the message handler.
+
      • 
+
+
    • LUA_ERRERR:  error while running the message handler.
      • 
+
+
    • LUA_ERRSYNTAX:  syntax error during precompilation.
      • 
+
+
    • LUA_YIELD:  the thread (coroutine) yields.
      • 
+
+
    • LUA_ERRFILE:  a file-related error;
+e.g., it cannot open or read the file.
      • 
+
+
    
+These constants are defined in the header file lua.h.
+
+
+
+
+
+
+
+
    4.5 – Handling Yields in C
    
 
 
    
 Internally, Lua uses the C longjmp facility to yield a coroutine.
@@ -3109,7 +3348,7 @@ 
    4.7 – Handling Yields in C
    
 and this API function yields
 (directly or indirectly by calling another function that yields),
 Lua cannot return to foo any more,
-because the longjmp removes its frame from the C stack.
+because the longjmp removes its frame from the C stack.
 
 
 
    
@@ -3139,7 +3378,7 @@ 
    4.7 – Handling Yields in C
    
 it eventually will finish running the callee function.
 However,
 the callee function cannot return to the original function,
-because its frame in the C stack was destroyed by the yield.
+because its frame in the C stack was destroyed by the yield.
 Instead, Lua calls a continuation function,
 which was given as an argument to the callee function.
 As the name implies,
@@ -3238,7 +3477,7 @@ 
    4.7 – Handling Yields in C
    
 
 
 
-
    4.8 – Functions and Types
    
+
    4.6 – Functions and Types
    
 
 
    
 Here we list all functions and types from the C API in
@@ -3259,7 +3498,7 @@ 
    4.8 – Functions and Types
    
 an interrogation mark '?' means that
 we cannot know how many elements the function pops/pushes
 by looking only at its arguments.
-(For instance, they may depend on what is on the stack.)
+(For instance, they may depend on what is in the stack.)
 The third field, x,
 tells whether the function may raise errors:
 '-' means the function never raises any error;
@@ -3278,7 +3517,7 @@ 
    4.8 – Functions and Types
    
 
    
 Converts the acceptable index idx
 into an equivalent absolute index
-(that is, one that does not depend on the stack top).
+(that is, one that does not depend on the stack size).
 
 
 
@@ -3353,7 +3592,7 @@ 
    4.8 – Functions and Types
    
          return realloc(ptr, nsize);
      }
 
    
-Note that Standard C ensures
+Note that ISO C ensures
 that free(NULL) has no effect and that
 realloc(NULL,size) is equivalent to malloc(size).
 
@@ -3405,7 +3644,7 @@ 
    4.8 – Functions and Types
    
 
    lua_CFunction lua_atpanic (lua_State *L, lua_CFunction panicf);
    
 
 
    
-Sets a new panic function and returns the old one (see §4.6).
+Sets a new panic function and returns the old one (see §4.4).
 
 
 
@@ -3417,11 +3656,15 @@ 
    4.8 – Functions and Types
    
 
 
    
 Calls a function.
+Like regular Lua calls,
+lua_call respects the __call metamethod.
+So, here the word "function"
+means any callable value.
 
 
 
    
 To do a call you must use the following protocol:
-first, the value to be called is pushed onto the stack;
+first, the function to be called is pushed onto the stack;
 then, the arguments to the call are pushed
 in direct order;
 that is, the first argument is pushed first.
@@ -3429,7 +3672,7 @@ 
    4.8 – Functions and Types
    
 nargs is the number of arguments that you pushed onto the stack.
 When the function returns,
 all arguments and the function value are popped
-and the function results are pushed onto the stack.
+and the call results are pushed onto the stack.
 The number of results is adjusted to nresults,
 unless nresults is LUA_MULTRET.
 In this case, all results from the function are pushed;
@@ -3443,8 +3686,6 @@ 
    4.8 – Functions and Types
    
 
    
 Any error while calling and running the function is propagated upwards
 (with a longjmp).
-Like regular Lua calls,
-this function respects the __call metamethod.
 
 
 
    
@@ -3484,7 +3725,7 @@ 
    4.8 – Functions and Types
    
 
 
    
 This function behaves exactly like lua_call,
-but allows the called function to yield (see §4.7).
+but allows the called function to yield (see §4.5).
 
 
 
@@ -3546,7 +3787,7 @@ 
    4.8 – Functions and Types
    
 
    int lua_checkstack (lua_State *L, int n);
    
 
 
    
-Ensures that the stack has space for at least n extra slots,
+Ensures that the stack has space for at least n extra elements,
 that is, that you can safely push up to n values into it.
 It returns false if it cannot fulfill the request,
 either because it would cause the stack
@@ -3554,7 +3795,7 @@ 
    4.8 – Functions and Types
    
 (typically at least several thousand elements) or
 because it cannot allocate memory for the extra space.
 This function never shrinks the stack;
-if the stack already has space for the extra slots,
+if the stack already has space for the extra elements,
 it is left unchanged.
 
 
@@ -3583,6 +3824,57 @@ 
    4.8 – Functions and Types
    
 
 
 
+
    lua_closeslot
    
+[-0, +0, e]
+
    void lua_closeslot (lua_State *L, int index);
    
+
+
    
+Close the to-be-closed slot at the given index and set its value to nil.
+The index must be the last index previously marked to be closed
+(see lua_toclose) that is still active (that is, not closed yet).
+
+
+
    
+A __close metamethod cannot yield
+when called through this function.
+
+
+
    
+(This function was introduced in release 5.4.3.)
+
+
+
+
+
+
    lua_closethread
    
+[-0, +?, –]
+
    int lua_closethread (lua_State *L, lua_State *from);
    
+
+
    
+Resets a thread, cleaning its call stack and closing all pending
+to-be-closed variables.
+Returns a status code:
+LUA_OK for no errors in the thread
+(either the original error that stopped the thread or
+errors in closing methods),
+or an error status otherwise.
+In case of error,
+leaves the error object on the top of the stack.
+
+
+
    
+The parameter from represents the coroutine that is resetting L.
+If there is no such coroutine,
+this parameter can be NULL.
+
+
+
    
+(This function was introduced in release 5.4.6.)
+
+
+
+
+
 
    lua_compare
    
 [-0, +0, e]
 
    int lua_compare (lua_State *L, int index1, int index2, int op);
    
@@ -3705,7 +3997,7 @@ 
    4.8 – Functions and Types
    
 
    int lua_error (lua_State *L);
    
 
 
    
-Generates a Lua error,
+Raises a Lua error,
 using the value on the top of the stack as the error object.
 This function does a long jump,
 and therefore never returns
@@ -3779,6 +4071,10 @@ 
    4.8 – Functions and Types
    
 see collectgarbage.
 
 
+
    
+This function should not be called by a finalizer.
+
+
 
 
 
@@ -4167,7 +4463,7 @@ 
    4.8 – Functions and Types
    
 
    typedef int (*lua_KFunction) (lua_State *L, int status, lua_KContext ctx);
    
 
 
    
-Type for continuation functions (see §4.7).
+Type for continuation functions (see §4.5).
 
 
 
@@ -4203,21 +4499,6 @@ 
    4.8 – Functions and Types
    
 Otherwise, it pushes an error message.
 
 
-
    
-The return values of lua_load are:
-
-
    
-
 
    
 The lua_load function uses a user-supplied reader function
 to read the chunk (see lua_Reader).
@@ -4226,7 +4507,7 @@ 
    4.8 – Functions and Types
    
 
 
    
 The chunkname argument gives a name to the chunk,
-which is used for error messages and in debug information (see §4.9).
+which is used for error messages and in debug information (see §4.7).
 
 
 
    
@@ -4243,10 +4524,17 @@ 
    4.8 – Functions and Types
    
 unmodified when returning.
 
 
+
    
+lua_load can return
+LUA_OK, LUA_ERRSYNTAX, or LUA_ERRMEM.
+The function may also return other values corresponding to
+errors raised by the read function (see §4.4.1).
+
+
 
    
 If the resulting function has upvalues,
 its first upvalue is set to the value of the global environment
-stored at index LUA_RIDX_GLOBALS in the registry (see §4.5).
+stored at index LUA_RIDX_GLOBALS in the registry (see §4.3).
 When loading main chunks,
 this upvalue will be the _ENV variable (see §2.2).
 Other upvalues are initialized with nil.
@@ -4319,6 +4607,10 @@ 
    4.8 – Functions and Types
    
 
 
    
 The function returns the address of the block of memory.
+Lua ensures that this address is valid as long as
+the corresponding userdata is alive (see §2.5).
+Moreover, if the userdata is marked for finalization (see §2.5.3),
+its address is valid at least until the call to its finalizer.
 
 
 
@@ -4333,7 +4625,7 @@ 
    4.8 – Functions and Types
    
 and pushes a key–value pair from the table at the given index,
 the "next" pair after the given key.
 If there are no more elements in the table,
-then lua_next returns 0 and pushes nothing.
+then lua_next returns 0 and pushes nothing.
 
 
 
    
@@ -4451,28 +4743,9 @@ 
    4.8 – Functions and Types
    
 
 
 
    
-The lua_pcall function returns one of the following constants
-(defined in lua.h):
+The lua_pcall function returns one of the following status codes:
+LUA_OK, LUA_ERRRUN, LUA_ERRMEM, or LUA_ERRERR.
 
-
    
 
 
 
@@ -4488,18 +4761,19 @@ 
    4.8 – Functions and Types
    
 
 
    
 This function behaves exactly like lua_pcall,
-but allows the called function to yield (see §4.7).
+except that it allows the called function to yield (see §4.5).
 
 
 
 
 
 
    lua_pop
    
-[-n, +0, –]
+[-n, +0, e]
 
    void lua_pop (lua_State *L, int n);
    
 
 
    
 Pops n elements from the stack.
+It is implemented as a macro over lua_settop.
 
 
 
@@ -4526,7 +4800,7 @@ 
    4.8 – Functions and Types
    
 and pushes onto the stack a Lua value of type function that,
 when called, invokes the corresponding C function.
 The parameter n tells how many upvalues this function will have
-(see §4.4).
+(see §4.2).
 
 
 
    
@@ -4540,7 +4814,7 @@ 
    4.8 – Functions and Types
    
 it is possible to associate some values with it,
 the so called upvalues;
 these upvalues are then accessible to the function whenever it is called.
-This association is called a C closure (see §4.4).
+This association is called a C closure (see §4.2).
 To create a C closure,
 first the initial values for its upvalues must be pushed onto the stack.
 (When there are multiple upvalues, the first value is pushed first.)
@@ -4583,7 +4857,7 @@ 
    4.8 – Functions and Types
    
 
 
    
 Pushes onto the stack a formatted string
-and returns a pointer to this string.
+and returns a pointer to this string (see §4.1.3).
 It is similar to the ISO C function sprintf,
 but has two important differences.
 First,
@@ -4683,7 +4957,7 @@ 
    4.8 – Functions and Types
    
 
 
 
    
-Returns a pointer to the internal copy of the string.
+Returns a pointer to the internal copy of the string (see §4.1.3).
 
 
 
@@ -4724,7 +4998,7 @@ 
    4.8 – Functions and Types
    
 
 
 
    
-Returns a pointer to the internal copy of the string.
+Returns a pointer to the internal copy of the string (see §4.1.3).
 
 
 
    
@@ -4794,6 +5068,7 @@ 
    4.8 – Functions and Types
    
 
    
 Similar to lua_gettable, but does a raw access
 (i.e., without metamethods).
+The value at index must be a table.
 
 
 
@@ -4807,7 +5082,7 @@ 
    4.8 – Functions and Types
    
 Pushes onto the stack the value t[n],
 where t is the table at the given index.
 The access is raw,
-that is, it does not invoke the __index metamethod.
+that is, it does not use the __index metavalue.
 
 
 
    
@@ -4826,7 +5101,7 @@ 
    4.8 – Functions and Types
    
 where t is the table at the given index and
 k is the pointer p represented as a light userdata.
 The access is raw;
-that is, it does not invoke the __index metamethod.
+that is, it does not use the __index metavalue.
 
 
 
    
@@ -4860,6 +5135,7 @@ 
    4.8 – Functions and Types
    
 
    
 Similar to lua_settable, but does a raw assignment
 (i.e., without metamethods).
+The value at index must be a table.
 
 
 
@@ -4878,7 +5154,7 @@ 
    4.8 – Functions and Types
    
 
    
 This function pops the value from the stack.
 The assignment is raw,
-that is, it does not invoke the __newindex metamethod.
+that is, it does not use the __newindex metavalue.
 
 
 
@@ -4898,7 +5174,7 @@ 
    4.8 – Functions and Types
    
 
    
 This function pops the value from the stack.
 The assignment is raw,
-that is, it does not invoke __newindex metamethod.
+that is, it does not use the __newindex metavalue.
 
 
 
@@ -4975,13 +5251,9 @@ 
    4.8 – Functions and Types
    
 
    int lua_resetthread (lua_State *L);
    
 
 
    
-Resets a thread, cleaning its call stack and closing all pending
-to-be-closed variables.
-Returns a status code:
-LUA_OK for no errors in closing methods,
-or an error status otherwise.
-In case of error,
-leaves the error object on the top of the stack,
+This function is deprecated;
+it is equivalent to lua_closethread with
+from being NULL.
 
 
 
@@ -4998,7 +5270,8 @@ 
    4.8 – Functions and Types
    
 
 
    
 To start a coroutine,
-you push onto the thread stack the main function plus any arguments;
+you push the main function plus any arguments
+onto the empty stack of the thread.
 then you call lua_resume,
 with nargs being the number of arguments.
 This call returns when the coroutine suspends or finishes its execution.
@@ -5011,14 +5284,15 @@ 
    4.8 – Functions and Types
    
 LUA_YIELD if the coroutine yields,
 LUA_OK if the coroutine finishes its execution
 without errors,
-or an error code in case of errors (see lua_pcall).
+or an error code in case of errors (see §4.4.1).
 In case of errors,
 the error object is on the top of the stack.
 
 
 
    
-To resume a coroutine, you clear its stack,
-push only the values to be passed as results from yield,
+To resume a coroutine,
+you remove the *nresults yielded values from its stack,
+push the values to be passed as results from yield,
 and then call lua_resume.
 
 
@@ -5132,8 +5406,9 @@ 
    4.8 – Functions and Types
    
 
    int lua_setmetatable (lua_State *L, int index);
    
 
 
    
-Pops a table from the stack and
-sets it as the new metatable for the value at the given index.
+Pops a table or nil from the stack and
+sets that value as the new metatable for the value at the given index.
+(nil means no metatable.)
 
 
 
    
@@ -5165,7 +5440,7 @@ 
    4.8 – Functions and Types
    
 
 
 
    lua_settop
    
-[-?, +?, –]
+[-?, +?, e]
 
    void lua_settop (lua_State *L, int index);
    
 
 
    
@@ -5176,6 +5451,11 @@ 
    4.8 – Functions and Types
    
 If index is 0, then all stack elements are removed.
 
 
+
    
+This function can run arbitrary code when removing an index
+marked as to-be-closed from the stack.
+
+
 
 
 
@@ -5225,7 +5505,7 @@ 
    4.8 – Functions and Types
    
 The status can be LUA_OK for a normal thread,
 an error code if the thread finished the execution
 of a lua_resume with an error,
-or LUA_YIELD if the thread is suspended.
+or LUA_YIELD if the thread is suspended.
 
 
 
    
@@ -5249,7 +5529,7 @@ 
    4.8 – Functions and Types
    
 that is, its length plus one.
 The conversion can result in an integer or a float,
 according to the lexical conventions of Lua (see §3.1).
-The string may have leading and trailing spaces and a sign.
+The string may have leading and trailing whitespaces and a sign.
 If the string is not a valid numeral,
 returns 0 and pushes nothing.
 (Note that the result can be used as a boolean,
@@ -5291,33 +5571,37 @@ 
    4.8 – Functions and Types
    
 
 
 
    lua_toclose
    
-[-0, +0, v]
+[-0, +0, m]
 
    void lua_toclose (lua_State *L, int index);
    
 
 
    
 Marks the given index in the stack as a
-to-be-closed "variable" (see §3.3.8).
+to-be-closed slot (see §3.3.8).
 Like a to-be-closed variable in Lua,
-the value at that index in the stack will be closed
+the value at that slot in the stack will be closed
 when it goes out of scope.
 Here, in the context of a C function,
 to go out of scope means that the running function returns to Lua,
-there is an error,
-or the index is removed from the stack through
-lua_settop or lua_pop.
-An index marked as to-be-closed should not be removed from the stack
-by any other function in the API except lua_settop or lua_pop.
+or there is an error,
+or the slot is removed from the stack through
+lua_settop or lua_pop,
+or there is a call to lua_closeslot.
+A slot marked as to-be-closed should not be removed from the stack
+by any other function in the API except lua_settop or lua_pop,
+unless previously deactivated by lua_closeslot.
 
 
 
    
 This function should not be called for an index
-that is equal to or below an active to-be-closed index.
+that is equal to or below an active to-be-closed slot.
 
 
 
    
-This function can raise an out-of-memory error.
-In that case, the value in the given index is immediately closed,
-as if it was already marked.
+Note that, both in case of errors and of a regular return,
+by the time the __close metamethod runs,
+the C stack was already unwound,
+so that any automatic C variable declared in the calling function
+(e.g., a buffer) will be out of scope.
 
 
 
@@ -5374,18 +5658,12 @@ 
    4.8 – Functions and Types
    
 
 
    
 lua_tolstring returns a pointer
-to a string inside the Lua state.
+to a string inside the Lua state (see §4.1.3).
 This string always has a zero ('\0')
 after its last character (as in C),
 but can contain other zeros in its body.
 
 
-
    
-Because Lua has garbage collection,
-there is no guarantee that the pointer returned by lua_tolstring
-will be valid after the corresponding Lua value is removed from the stack.
-
-
 
 
 
@@ -5533,7 +5811,7 @@ 
    4.8 – Functions and Types
    
 
 
    
 Returns the pseudo-index that represents the i-th upvalue of
-the running function (see §4.4).
+the running function (see §4.2).
 i must be in the range [1,256].
 
 
@@ -5635,7 +5913,7 @@ 
    4.8 – Functions and Types
    
 
 
    
 This function is equivalent to lua_yieldk,
-but it has no continuation (see §4.7).
+but it has no continuation (see §4.5).
 Therefore, when the thread resumes,
 it continues the function that called
 the function calling lua_yield.
@@ -5668,7 +5946,7 @@ 
    4.8 – Functions and Types
    
 
    
 When the coroutine is resumed again,
 Lua calls the given continuation function k to continue
-the execution of the C function that yielded (see §4.7).
+the execution of the C function that yielded (see §4.5).
 This continuation function receives the same stack
 from the previous function,
 with the n results removed and
@@ -5684,7 +5962,7 @@ 
    4.8 – Functions and Types
    
 it continues executing the continuation function.
 However, there is one special case,
 which is when this function is called
-from inside a line or a count hook (see §4.9).
+from inside a line or a count hook (see §4.7).
 In that case, lua_yieldk should be called with no continuation
 (probably in the form of lua_yield) and no results,
 and the hook should return immediately after the call.
@@ -5707,7 +5985,7 @@ 
    4.8 – Functions and Types
    
 
 
 
-
    4.9 – The Debug Interface
    
+
    4.7 – The Debug Interface
    
 
 
    
 Lua has no built-in debugging facilities.
@@ -5747,7 +6025,10 @@ 
    4.9 – The Debug Interface
    
 lua_getstack fills only the private part
 of this structure, for later use.
 To fill the other fields of lua_Debug with useful information,
-you must call lua_getinfo.
+you must call lua_getinfo with an appropriate parameter.
+(Specifically, to get a field,
+you must add the letter between parentheses in the field's comment
+to the parameter what of lua_getinfo.)
 
 
 
    
@@ -5761,7 +6042,7 @@ 
    4.9 – The Debug Interface
    
 it means that the function was defined in a file where
 the file name follows the '@'.
 If source starts with a '=',
-the remainder of its contents describe the source in a user-dependent manner.
+the remainder of its contents describes the source in a user-dependent manner.
 Otherwise,
 the function was defined in a string where
 source is that string.
@@ -5831,12 +6112,12 @@ 
    4.9 – The Debug Interface
  • isvararg: -true if the function is a vararg function +true if the function is a variadic function (always true for C functions).
  • ftransfer: -the index on the stack of the first value being "transferred", +the index in the stack of the first value being "transferred", that is, parameters in a call or return values in a return. (The other values are in consecutive indices.) Using this index, you can access and modify these values @@ -5924,11 +6205,25 @@

    4.9 – The Debug Interface

    Each character in the string what selects some fields of the structure ar to be filled or -a value to be pushed on the stack: +a value to be pushed on the stack. +(These characters are also documented in the declaration of +the structure lua_Debug, +between parentheses in the comments following each field.)