Module: DSLCompose::Composer

Defined in:
lib/dsl_compose/composer.rb

Defined Under Namespace

Classes: ComposerAlreadyInstalledError, GetDSLExecutionResultsMethodAlreadyExistsError, MethodAlreadyExistsWithThisDSLNameError

Class Method Summary collapse

Class Method Details

.included(klass) ⇒ Object 



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# File 'lib/dsl_compose/composer.rb', line 14

def self.included klass
  if (klass.private_methods + klass.methods).include? :define_dsl
    raise ComposerAlreadyInstalledError, "This module has already been included or the define_dsl singleton method already exists for this class."
  end

  # create an interpreter for this class which will be shared by all child classes and all
  # the dynamicly defined DSLs in this class
  interpreter = DSLCompose::Interpreter.new

  # return a specific DSL which is defined for this class
  if klass.respond_to? :dsls
    raise GetDSLExecutionResultsMethodAlreadyExistsError, "The `dsls` singleton method already exists for this class."
  end

  klass.define_singleton_method :dsls do
    interpreter
  end

  # return a specific DSL which is defined for this class
  klass.define_singleton_method :define_dsl do |name, &block|
    # Find or create a DSL with this name for the provided class. We allow an existing
    # DSL to be accessed so that it can be be extended (have new methods added to it).
    # `self` here is the class in which `define_dsl` is being called
    if DSLCompose::DSLs.class_dsl_exists? self, name
      # get the existing DSL
      dsl = DSLCompose::DSLs.class_dsl self, name

    else
      dsl = DSLCompose::DSLs.create_dsl self, name

      # ensure that creating this DSL will not override any existing methods on this class
      if respond_to? name
        raise MethodAlreadyExistsWithThisDSLNameError, "The `define_dsl` singleton method `#{name}` already exists for this class."
      end

      # add a singleton method with the name of this new DSL onto our class, this is how our new DSL will be accessed
      define_singleton_method name do |*args, &block|
        called_from = caller(1..1).first

        # when it is called, we process this new dynamic DSL with the interpreter
        # `self` here is the class in which the dsl is being used, not the class in which the DSL was defined
        interpreter.execute_dsl self, dsl, called_from, *args, &block
      end

    end

    # evaluate the configuration block which uses our internal DSL to define this dynamic DSL
    if block
      dsl.evaluate_configuration_block(&block)
    end
  end
end