intro
ScriptBasic for Java is a scripting implementation of the classic basic language. Using this interpreter you can extend your application with BASIC scripting possibilities. There are many scripting languages that can be embedded in a Java application. Different languages have different capabilities and different target users' group. ScriptBasic for Java targets the applications that are to be extended using scripts by users who are not really programmers.
Business analysts, domain experts who use an application can learn Groovy, JavaScript, Python or some other scripting language to program the scripting possibilities of the application.
They will not learn. Probably.
In the case of BASIC, this learning is not needed. If any programming is known already then it is BASIC. This also means that the "freak out" factor is minimal. Your prospective users may freak out hearing that the application can be scripted using Groovy, JavaScript or Python which all are considered geek languages. In the case of BASIC, this does not happen. If the prospective users have a minimal affinity to programming they have some experience using Excel and its BASIC, Visual Basic or just any other BASIC generally.
For the same reason, the language implemented is very simple. It implements only a very limited set of commands and operators. Only those commands are implemented which are needed to create embedded scripts. Nothing more.
You can assign values to variables, loop, execute conditional code (IF statement), print to the standard output and call subroutines. You can handle arrays. Is there anything else you need in a BASIC script?
Well, yes.
You may need to communicate with the embedding host application more than just printing to the output. The program can call Java static methods if they are configured to be available for the script. The program can also call an instance method in case the object is stored in a BASIC variable and if the host application made that possible. To do that the usual object.method(params) format can be used, or just method(params) when it is not ambiguous.
Script languages may pose security risks if not properly configured. When you start a Python, JavaScript of Groovy script it can access the application Java objects, methods and so on. You have to pay great attention to execute other language scripts securely setting up SecurityManager to avoid a hacking script run amok. For this reason, these languages are not used as a user-definable extension script possibility.
BASIC programs executed by the ScriptBasic interpreter can not do that unless the host application explicitly made some of the methods and objects available for the code. The host application can even limit the number of steps, or the maximum time a BASIC program can execute and then terminate the execution with error, which is very handy when a BASIC script gets into an infinite loop or endless recursion.
To embed ScriptBasic for Java into a host application the host application can use the standard
JSR-223 interface. This way you can embed just any scripting language easily without further programming.
As a matter of fact the main() method of the class com.scriptbasic.main.CommandLine uses solely
this interface and as a side effect you can use the command-line version of ScriptBasic for Java to execute
JavaScript, Python, Groovy or any other scripts if their interpreter is on the class-path.
If an application properly uses the JRS-223 interface, integrating jScriptBasic as another scripting language
to the application is simply adding the jscriptbasic-${project.version}.jar file on the classpath and restart the application.
You can also execute BASIC programs from the command line. All you have to do is issue the command line
java -jar jscriptbasic-${project.version}.jar basicProgram.sb
and the program in the file basicProgram.sb will execute. (Note that the line above uses the latest version
${project.version} which may not be the latest released version. If it finishes with the postfix -SNAPSHOT
then the version is a development version. Instead, use the name of the JAR file you downloaded.)
