Module: Autoload

Defined in:
lib/autoload.rb

Overview

Autoload allows you to specify which modules or classes to automatically load when they are referenced. This is somewhat more sophisticated than the autoinclude mechanism in the standard library. For one thing, you can cause code to be reloaded by using Reloadable in conjunction with Autoload. For another, you can provide a search path using the directories method, thereby allowing you to “autoinclude” entire directories in one fell swoop.

To use Autoload, you must mix it into your module or class via extend. That will provide the autoload and directories methods for you, as described below.

A typical use case for Autoload looks like this:

require 'autocode'

module Models
  extend Autoload; extend Reloadable
  autoload true; directories :models
end

Class Method Summary collapse

Class Method Details

.extended(mod) ⇒ Object

:nodoc:



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# File 'lib/autoload.rb', line 19

def self.extended( mod ) #:nodoc:

	old = mod.method( :const_missing )
	
	mod.metaclass.class_eval do

		# Specifies that you want to autoload each of the constants referenced by keys. A key of true is basically a wild-card, meaning "load anything". 
		def autoload( *keys )
			( @autoload ||= [] ).concat(keys)
			return self
		end
		
		# Provide a list of directories from which a given constant might be loaded.
		def directories( *dirs )
			( @directories ||= ['.'] ).concat(dirs)
			return self
		end
		
		# Is a given constant being autoloaded?
		def autoload?( cname )

			cname = cname.to_s.gsub(/([a-z\d])([A-Z])/){ "#{$1}_#{$2.downcase}"}
			
			# is this name autoloadable?
			key = ( @autoload ||= [] ).find do |key| 
				key == true || ( key.to_s == cname )
			end
			
		end

		define_method :const_missing do | cname | #:nodoc:
			
			return old.call(cname) unless autoload?( cname )
			fname = ( cname.to_s.gsub(/([a-z\d])([A-Z])/){ "#{$1}_#{$2.downcase}"} + '.rb' ).downcase
			dir = ( @directories ||= ['.'] ).find do |dir|
				File.exist?( dir / fname )
			end
			
			if ( dir && load( dir / fname ) && c = const_get( cname ) )
				( @reloadable ||= [] ) << cname; return c
			else 
				old.call( cname )
			end
			
		end
	
	end
	
end