diff options
author | matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2005-09-26 13:59:47 +0000 |
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committer | matz <matz@b2dd03c8-39d4-4d8f-98ff-823fe69b080e> | 2005-09-26 13:59:47 +0000 |
commit | 81b728c2436bfd94abe33b152493bc5b7a3a1728 (patch) | |
tree | 2145042614c2bc1daad13f7c3def31dd31d09bff /lib/delegate.rb | |
parent | 54ca4e2269ffd818dcd2bd36ea474c03e1ad64af (diff) |
* eval.c (set_trace_func): add rb_secure(4) to prevent adding
tracing function.
* lib/delegate.rb: document update from James Edward Gray II
<james@grayproductions.net>. [ruby-core:05942]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_8@9317 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Diffstat (limited to 'lib/delegate.rb')
-rw-r--r-- | lib/delegate.rb | 191 |
1 files changed, 170 insertions, 21 deletions
diff --git a/lib/delegate.rb b/lib/delegate.rb index ca1f028268..2a0119d082 100644 --- a/lib/delegate.rb +++ b/lib/delegate.rb @@ -1,23 +1,125 @@ -# Delegation class that delegates even methods defined in super class, -# which can not be covered with normal method_missing hack. -# -# Delegator is the abstract delegation class. Need to redefine -# `__getobj__' method in the subclass. SimpleDelegator is the -# concrete subclass for simple delegation. +# = delegate -- Support for the Delegation Pattern # -# Usage: -# foo = Object.new -# foo2 = SimpleDelegator.new(foo) -# foo.hash == foo2.hash # => false +# Documentation by James Edward Gray II and Gavin Sinclair # -# Foo = DelegateClass(Array) +# == Introduction # -# class ExtArray<DelegateClass(Array) -# ... -# end +# This library provides three different ways to delegate method calls to an +# object. The easiest to use is SimpleDelegator. Pass an object to the +# constructor and all methods supported by the object will be delegated. This +# object can be changed later. +# +# Going a step further, the top level DelegateClass method allows you to easily +# setup delegation through class inheritance. This is considerably more +# flexible and thus probably the most common use for this library. +# +# Finally, if you need full control over the delegation scheme, you can inherit +# from the abstract class Delegator and customize as needed. (If you find +# yourself needing this control, have a look at _forwardable_, also in the +# standard library. It may suit your needs better.) +# +# == Notes +# +# Be advised, RDoc will not detect delegated methods. +# +# <b>delegate.rb provides full-class delegation via the +# DelegateClass() method. For single-method delegation via +# def_delegator(), see forwardable.rb.</b> +# +# == Examples +# +# === SimpleDelegator +# +# Here's a simple example that takes advantage of the fact that +# SimpleDelegator's delegation object can be changed at any time. +# +# class Stats +# def initialize +# @source = SimpleDelegator.new([]) +# end +# +# def stats( records ) +# @source.__setobj__(records) +# +# "Elements: #{@source.size}\n" + +# " Non-Nil: #{@source.compact.size}\n" + +# " Unique: #{@source.uniq.size}\n" +# end +# end +# +# s = Stats.new +# puts s.stats(%w{James Edward Gray II}) +# puts +# puts s.stats([1, 2, 3, nil, 4, 5, 1, 2]) +# +# <i>Prints:</i> +# +# Elements: 4 +# Non-Nil: 4 +# Unique: 4 +# +# Elements: 8 +# Non-Nil: 7 +# Unique: 6 +# +# === DelegateClass() +# +# Here's a sample of use from <i>tempfile.rb</i>. +# +# A _Tempfile_ object is really just a _File_ object with a few special rules +# about storage location and/or when the File should be deleted. That makes for +# an almost textbook perfect example of how to use delegation. +# +# class Tempfile < DelegateClass(File) +# # constant and class member data initialization... +# +# def initialize(basename, tmpdir=Dir::tmpdir) +# # build up file path/name in var tmpname... +# +# @tmpfile = File.open(tmpname, File::RDWR|File::CREAT|File::EXCL, 0600) +# +# # ... +# +# super(@tmpfile) +# +# # below this point, all methods of File are supported... +# end +# +# # ... +# end +# +# === Delegator +# +# SimpleDelegator's implementation serves as a nice example here. +# +# class SimpleDelegator < Delegator +# def initialize(obj) +# super # pass obj to Delegator constructor, required +# @_sd_obj = obj # store obj for future use +# end +# +# def __getobj__ +# @_sd_obj # return object we are delegating to, required +# end +# +# def __setobj__(obj) +# @_sd_obj = obj # change delegation object, a feature we're providing +# end +# +# # ... +# end +# +# Delegator is an abstract class used to build delegator pattern objects from +# subclasses. Subclasses should redefine \_\_getobj\_\_. For a concrete +# implementation, see SimpleDelegator. +# class Delegator + # + # Pass in the _obj_ to delegate method calls to. All methods supported by + # _obj_ will be delegated to. + # def initialize(obj) preserved = ::Kernel.public_instance_methods(false) preserved -= ["to_s","to_a","inspect","==","=~","==="] @@ -49,6 +151,7 @@ class Delegator end alias initialize_methods initialize + # Handles the magic of delegation through \_\_getobj\_\_. def method_missing(m, *args) target = self.__getobj__ unless target.respond_to?(m) @@ -57,23 +160,39 @@ class Delegator target.__send__(m, *args) end + # + # Checks for a method provided by this the delegate object by fowarding the + # call through \_\_getobj\_\_. + # def respond_to?(m) return true if super return self.__getobj__.respond_to?(m) end + # + # This method must be overridden by subclasses and should return the object + # method calls are being delegated to. + # def __getobj__ raise NotImplementedError, "need to define `__getobj__'" end + # Serialization support for the object returned by \_\_getobj\_\_. def marshal_dump __getobj__ end + # Reinitializes delegation from a serialized object. def marshal_load(obj) initialize_methods(obj) end end +# +# A concrete implementation of Delegator, this class provides the means to +# delegate all supported method calls to the object passed into the constructor +# and even to change the object being delegated to at a later time with +# \_\_setobj\_\_ . +# class SimpleDelegator<Delegator def initialize(obj) @@ -81,61 +200,89 @@ class SimpleDelegator<Delegator @_sd_obj = obj end + # Returns the current object method calls are being delegated to. def __getobj__ @_sd_obj end + # + # Changes the delegate object to _obj_. + # + # It's important to note that this does *not* cause SimpleDelegator's methods + # to change. Because of this, you probably only want to change delegation + # to objects of the same type as the original delegate. + # + # Here's an example of changing the delegation object. + # + # names = SimpleDelegator.new(%w{James Edward Gray II}) + # puts names[1] # => Edward + # names.__setobj__(%w{Gavin Sinclair}) + # puts names[1] # => Sinclair + # def __setobj__(obj) raise ArgumentError, "cannot delegate to self" if self.equal?(obj) @_sd_obj = obj end + # Clone support for the object returned by \_\_getobj\_\_. def clone super __setobj__(__getobj__.clone) end + # Duplication support for the object returned by \_\_getobj\_\_. def dup(obj) super __setobj__(__getobj__.dup) end end +# :stopdoc: # backward compatibility ^_^;;; Delegater = Delegator SimpleDelegater = SimpleDelegator +# :startdoc: # +# The primary interface to this library. Use to setup delegation when defining +# your class. +# +# class MyClass < DelegateClass( ClassToDelegateTo ) # Step 1 +# def initiaize +# super(obj_of_ClassToDelegateTo) # Step 2 +# end +# end +# def DelegateClass(superclass) klass = Class.new methods = superclass.public_instance_methods(true) methods -= ::Kernel.public_instance_methods(false) methods |= ["to_s","to_a","inspect","==","=~","==="] klass.module_eval { - def initialize(obj) + def initialize(obj) # :nodoc: @_dc_obj = obj end - def method_missing(m, *args) + def method_missing(m, *args) # :nodoc: unless @_dc_obj.respond_to?(m) super(m, *args) end @_dc_obj.__send__(m, *args) end - def respond_to?(m) + def respond_to?(m) # :nodoc: return true if super return @_dc_obj.respond_to?(m) end - def __getobj__ + def __getobj__ # :nodoc: @_dc_obj end - def __setobj__(obj) + def __setobj__(obj) # :nodoc: raise ArgumentError, "cannot delegate to self" if self.equal?(obj) @_dc_obj = obj end - def clone + def clone # :nodoc: super __setobj__(__getobj__.clone) end - def dup + def dup # :nodoc: super __setobj__(__getobj__.dup) end @@ -159,6 +306,8 @@ def DelegateClass(superclass) return klass end +# :enddoc: + if __FILE__ == $0 class ExtArray<DelegateClass(Array) def initialize() |