Module: EcoRake::Default::Const::ClassMethods

Defined in:
lib/eco-rake/default/const.rb

Instance Method Summary collapse

Instance Method Details

#attr_const(*attrs, required: false, override: false, default: :not_used) ⇒ Object

Note:

this creates one method on the class and one on instances thereof.

Creates (overridable) method(s) that link to an expected constant with same name (in capitals).

Parameters:

  • required (Boolean) (defaults to: false) —

    whether an exception should be raised if the constant does not exist when the created method is called.

  • override (Boolean) (defaults to: false) —

    whether an exception should NOT be raised if the method exists.

  • default (Variant) (defaults to: :not_used) —

    whether if this defaults to some value (won't raise NameError).



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# File 'lib/eco-rake/default/const.rb', line 19

def attr_const(*attrs, required: false, override: false, default: :not_used)
  attrs.each do |attr|
    attr = attr.to_s.freeze

    unless override
      msg  = "#{__method__} does not allow method override. Offending attr: #{attr}"
      raise ArgumentError, "#{msg} (class method)"    if methods.include?(attr)
      raise ArgumentError, "#{msg} (instance method)" if instance_methods.include?(attr)
    end

    define_singleton_method attr do
      value = resolve_const(attr)
      value = default if value.nil? && default != :not_used

      msg   = "Missing const '#{attr.to_s.upcase}' in #{self}"
      raise NameError, msg if value.nil? && required

      yield(value) if block_given?
      value
    end

    define_method attr do |&block|
      self.class.send(attr, &block)
    end
  end
end