feat: Replaced returns kwarg with block or hashrocket - the choice is yours!

fixes #5

Author: joelmoss

.rubocop.yml

@@ -5,6 +5,11 @@ AllCops:
 
 Style/Documentation:
   Enabled: false
+Style/HashAsLastArrayItem:
+  Enabled: false
+
+Layout/LineLength:
+  Max: 100
 
 Lint/ConstantDefinitionInBlock:
   Exclude:
@@ -14,6 +19,10 @@ Metrics/AbcSize:
   Enabled: false
 Metrics/MethodLength:
   Enabled: false
+Metrics/CyclomaticComplexity:
+  Enabled: false
+Metrics/PerceivedComplexity:
+  Enabled: false
 
 Metrics/BlockLength:
   Exclude:

README.md

@@ -5,15 +5,16 @@ runtime. This is useful for ensuring that your methods are being called with the
 and for providing better error messages when they are not. It also serves as a nice way of
 documenting your methods using actual code instead of comments.
 
+## Usage
+
 Simply define a method signature using the `sig` method directly before the method to be checked,
-and Delivered will check that the method is being called with the correct arguments and types. it
-can also check the return value of the method if you pass `sig` a `returns` keyword argument.
+and Delivered will check that the method is being called with the correct arguments and types.
 
 ```ruby
 class User
   extend Delivered::Signature
 
-  sig String, age: Integer, returns: String
+  sig String, age: Integer
   def create(name, age:)
     "User #{name} created with age #{age}"
   end
@@ -22,3 +23,24 @@ end
 
 If an invalid argument is given to `User#create`, for example, if `age` is a `String` instead of
 the required `Integer`, a `NoMatchingPatternError` exception will be raised.
+
+### Return Types
+
+You can also check the return value of the method by passing a Hash with an Array as the key, and
+the value as the return type to check.
+
+```ruby
+sig [String, age: Integer] => String
+def create(name, age:)
+  "User #{name} created with age #{age}"
+end
+```
+
+Or by placing the return type in a block to `sig`.
+
+```ruby
+sig(String, age: Integer) { String }
+def create(name, age:)
+  "User #{name} created with age #{age}"
+end
+```

lib/delivered/signature.rb

@@ -4,9 +4,29 @@ module Delivered
   module Signature
     NULL = Object.new
 
-    def sig(*sig_args, returns: NULL, **sig_kwargs)
+    def sig(*sig_args, **sig_kwargs, &return_blk)
+      # ap [sig_args, sig_kwargs, return_blk]
+
+      # Block return
+      returns = return_blk&.call
+
+      # Hashrocket return
+      if sig_kwargs.keys[0].is_a?(Array)
+        unless returns.nil?
+          raise ArgumentError, 'Cannot mix block and hash for return type. Use one or the other.'
+        end
+
+        returns = sig_kwargs.values[0]
+        sig_args = sig_kwargs.keys[0]
+        sig_kwargs = sig_args.pop
+      end
+
+      # ap sig_args
+      # ap sig_kwargs
+      # ap returns
+
       meta = class << self; self; end
-      sig_check = lambda { |klass, name, *args, **kwargs, &block|
+      sig_check = lambda do |klass, name, *args, **kwargs, &block|
         sig_args.each.with_index do |arg, i|
           args[i] => ^arg
         end
@@ -21,10 +41,11 @@ def sig(*sig_args, returns: NULL, **sig_kwargs)
                    klass.send(:"__#{name}", *args, **kwargs)
                  end
 
-        result => ^returns if returns != NULL
+        result => ^returns unless returns.nil?
 
         result
-      }
+      end
+
       meta.send :define_method, :method_added do |name|
         meta.send :remove_method, :method_added
         meta.send :remove_method, :singleton_method_added

test/delivered/signature.rb

@@ -6,59 +6,104 @@ class User
 
     attr_reader :town, :blk
 
-    sig String, Integer, town: String
+    sig(Integer) { Integer }
+    attr_writer :age
+
+    sig String, town: String
     def initialize(name, age = nil, town: nil, &block)
       @name = name
       @age = age
       @town = town
       @blk = block
     end
 
-    sig returns: String
+    sig(String, age: Integer) { Integer }
+    def with_block_return(name, age:) = 1 # rubocop:disable Lint/UnusedMethodArgument
+
+    sig(String, age: Integer) { Integer }
+    def with_incorrect_block_return = 'hello'
+
+    sig [String, age: Integer] => Integer
+    def with_incorrect_hash_return = 'hello'
+
+    sig [String, age: Integer] => Integer
+    def with_hash_return(name, age:) = 1 # rubocop:disable Lint/UnusedMethodArgument
+
+    sig [] => String
     def to_s = "#{@name}, #{@age}"
 
-    sig returns: Integer
+    sig { Integer }
     def age = @age.to_s
 
-    sig Integer, returns: Integer
-    attr_writer :age
+    sig(String, _age: Integer) { Array }
+    def self.where(_name, _age: nil) = []
+
+    sig [String] => Array
+    def self.find_by_name(name) = User.new(name)
+  end
 
-    sig String, _age: Integer, returns: Array
-    def self.where(_name, _age: nil)
-      []
+  with 'return type with hash' do
+    it 'succeeds' do
+      user = User.new('Joel')
+      expect(user.with_hash_return('Joel', age: 47)).to be == 1
     end
 
-    sig String, returns: Array
-    def self.find_by_name(name)
-      User.new(name)
+    it 'raises on incorrect types' do
+      user = User.new('Joel')
+      expect { user.with_hash_return }.to raise_exception NoMatchingPatternError
+    end
+
+    it 'raises on incorrect return type' do
+      user = User.new('Joel')
+      expect { user.with_incorrect_hash_return }.to raise_exception NoMatchingPatternError
     end
   end
 
-  it 'supports positional args' do
-    user = User.new('Joel', 47)
-    expect(user.to_s).to be == 'Joel, 47'
+  with 'return type as block' do
+    it 'succeeds' do
+      user = User.new('Joel')
+      expect(user.with_block_return('Joel', age: 47)).to be == 1
+    end
+
+    it 'raises on incorrect types' do
+      user = User.new('Joel')
+      expect { user.with_block_return }.to raise_exception NoMatchingPatternError
+    end
+
+    it 'raises on incorrect return type' do
+      user = User.new('Joel')
+      expect { user.with_incorrect_block_return }.to raise_exception NoMatchingPatternError
+    end
   end
 
-  # it 'supports optional positional args'
+  it 'raises on mix of returns' do
+    extend Delivered::Signature
 
-  it 'supports block' do
-    user = User.new('Joel', 47) { 'Hello' }
-    expect(user.blk.call).to be == 'Hello'
+    expect do
+      sig([] => Integer) { Integer }
+    end.to raise_exception(ArgumentError, message: be =~ /Cannot mix/)
   end
 
-  it 'checks return type' do
+  it 'supports positional args' do
     user = User.new('Joel', 47)
     expect(user.to_s).to be == 'Joel, 47'
   end
 
-  it 'raises on incorrect return type' do
-    user = User.new('Joel', 47)
-    expect { user.age }.to raise_exception NoMatchingPatternError
+  it 'supports block' do
+    user = User.new('Joel', 47) { 'Hello' }
+    expect(user.blk.call).to be == 'Hello'
   end
 
-  it 'checks return type with args' do
-    user = User.new('Joel', 47)
-    expect(user.age = 48).to be == 48
+  with 'attr_writer' do
+    it 'succeeds' do
+      user = User.new('Joel')
+      expect(user.age = 47).to be == 47
+    end
+
+    it 'raise on incorrect type' do
+      user = User.new('Joel', 47)
+      expect { user.age = '47' }.to raise_exception NoMatchingPatternError
+    end
   end
 
   it 'raises on missing args' do