Mixins::

Delegation module

A collection of various delegation code-generators that can be used to define delegation through other methods, to instance variables, etc.

Public Instance Methods

def_class_delegators( *delegated_methods )

Define the given delegated_methods as delegators to the like-named class method.

# File lib/mixins/delegation.rb, line 55
def def_class_delegators( *delegated_methods )
        delegated_methods.each do |name|
                define_method( name ) do |*args|
                        self.class.__send__( name, *args )
                end
        end
end

def_ivar_delegators( ivar, *delegated_methods )

Define the given delegated_methods as delegators to the like-named method of the specified ivar. This is pretty much identical with how ‘Forwardable’ from the stdlib does delegation, but it’s reimplemented here for consistency.

class MyClass
  extend Mixins::Delegation

  # Delegate the #each method to the @collection ivar
  def_ivar_delegators :@collection, :each

end

# File lib/mixins/delegation.rb, line 45
def def_ivar_delegators( ivar, *delegated_methods )
        delegated_methods.each do |name|
                body = Mixins::Delegation.make_ivar_delegator( ivar, name )
                define_method( name, &body )
        end
end

def_method_delegators( delegate_method, *delegated_methods )

Define the given delegated_methods as delegators to the like-named method of the return value of the delegate_method.

class MyClass
  extend Mixins::Delegation

  # Delegate the #bound?, #err, and #result2error methods to the connection
  # object returned by the #connection method. This allows the connection
  # to still be loaded on demand/overridden/etc.
  def_method_delegators :connection, :bound?, :err, :result2error

  def connection
    @connection ||= self.connect
  end
end

# File lib/mixins/delegation.rb, line 25
def def_method_delegators( delegate_method, *delegated_methods )
        delegated_methods.each do |name|
                body = Mixins::Delegation.make_method_delegator( delegate_method, name )
                define_method( name, &body )
        end
end

make_ivar_delegator( ivar_name, name )

Make the body of a delegator method that will delegate calls to the name method to the given ivar.

# File lib/mixins/delegation.rb, line 83
def make_ivar_delegator( ivar_name, name )
        return ->( *args, **kwargs, &block ) do
                ivar = self.instance_variable_get( ivar_name )
                ivar.__send__( name, *args, **kwargs, &block )
        rescue => err
                bt = err.backtrace_locations
                bt.shift
                raise( err, err.message, bt, cause: err )
        end
end

make_method_delegator( delegate, name )

Make the body of a delegator method that will delegate to the name method of the object returned by the delegate method.

# File lib/mixins/delegation.rb, line 70
def make_method_delegator( delegate, name )
        return ->( *args, **kwargs, &block ) do
                self.__send__( delegate ).__send__( name, *args, **kwargs, &block )
        rescue => err
                bt = err.backtrace_locations
                bt.shift
                raise( err, err.message, bt, cause: err )
        end
end