Module: ConstReader

Defined in:
lib/scripref/const_reader.rb

Overview

Mixin to generate instance methods to access of mixin constants.

Example:

module M
  A = :a
  B = :b
  extend ConstReader
  const_reader constants
end

# Include in class
class C
  include M
end
c = C.new
c.a # => :a
c.b # => :b

# Extend an instance
o = Object.new
o.extend M
o.a # => :a
o.b # => :b

Instance Method Summary collapse

Instance Method Details

#const_accessor(*consts) ⇒ Object

Define a getter and a setter method for one or more constant values. The value of the constant itself is not changed, instead a corresponding instance variable is used.

Example:

module M
  A = :ma
  extend ConstReader
  const_accessor :A
end
class C
  include M
end
c1 = C.new
c1.a # => :ma
c1.a = :ca
c1.a # => :ca
c2 = C.new
c2.a # => :ma



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# File 'lib/scripref/const_reader.rb', line 65

def const_accessor *consts
  consts.flatten.each do |c|
    class_exec(c.to_s, c.to_s.downcase) do |c_name, m_name|
      define_method m_name do
        ivar = '@' << m_name
        if instance_variable_defined? ivar
          return instance_variable_get(ivar)
        else
          val = self.singleton_class.const_get c_name
          instance_variable_set ivar, val
          return val
        end
      end
      attr_writer m_name
    end
  end
end

#const_reader(*consts) ⇒ Object

Define a getter method for one or more constants.

Example:

# all defined constants
const_reader constants

# constants A and B
const_reader :A, :B



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# File 'lib/scripref/const_reader.rb', line 36

def const_reader *consts
  consts.flatten.each do |c|
    class_exec(c.to_s, c.to_s.downcase) do |c_name, m_name|
      define_method m_name do
        self.singleton_class.const_get c_name
      end
    end
  end
end