ruby-core

On Sep 22, 2005, at 9:02 AM, James Edward Gray II wrote:

> These files are documented copies of the Delegate and Forwardable  
> libraries that Gavin Sinclair and I wrote back in December.
>
>
>
>

Looks like delegate changed quite a bit between December and now.   
Here's updated documentation, in diff form this time.

Can this be applied?

James Edward Gray II

Attachments (1)

forwardable_and_delegate_docs.diff (12.7 KB, text/x-diff)

Index: lib/.document
===================================================================
RCS file: /src/ruby/lib/.document,v
retrieving revision 1.8
diff -r1.8 .document
16a17,18
> delegate.rb
> erb.rb
18a21
> forwardable.rb
Index: lib/delegate.rb
===================================================================
RCS file: /src/ruby/lib/delegate.rb,v
retrieving revision 1.28
diff -r1.28 delegate.rb
1,17c1,110
< #  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.
< #
< # Usage:
< #   foo = Object.new
< #   foo2 = SimpleDelegator.new(foo)
< #   foo.hash == foo2.hash # => false
< #
< #   Foo = DelegateClass(Array)
< #
< #  class ExtArray<DelegateClass(Array)
< #    ...
< #  end
---
> # = delegate -- Support for the Delegation Pattern
> #
> # Documentation by James Edward Gray II and Gavin Sinclair
> #
> # == Introduction
> #
> # 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
18a112,116
> #
> # Delegator is an abstract class used to build delegator pattern objects from
> # subclasses.  Subclasses should redefine \_\_getobj\_\_.  For a concrete
> # implementation, see SimpleDelegator.
> #
25a124,127
>   #
>   # Pass in the _obj_ to delegate method calls to.  All methods supported by
>   # _obj_ will be delegated to.
>   #
29a132
>   # Handles the magic of delegation through \_\_getobj\_\_.
42a146,149
>   # 
>   # Checks for a method provided by this the delegate object by fowarding the 
>   # call through \_\_getobj\_\_.
>   # 
47a155,158
>   #
>   # This method must be overridden by subclasses and should return the object
>   # method calls are being delegated to.
>   #
51a163,166
>   #
>   # This method must be overridden by subclasses and change the object delegate
>   # to _obj_.
>   #
55a171
>   # Serialization support for the object returned by \_\_getobj\_\_.
58a175
>   # Reinitializes delegation from a serialized object.
63a181,186
> #
> # 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\_\_ .
> #
64a188
>   # Returns the current object method calls are being delegated to.
68a193,206
>   #
>   # 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
>   #
73a212
>   # Clone support for the object returned by \_\_getobj\_\_.
78a218
>   # Duplication support for the object returned by \_\_getobj\_\_.
85a226
> # :stopdoc:
88a230
> # :startdoc:
90a233,241
> # 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
> #
100c251
<     def initialize(obj)
---
>     def initialize(obj)  # :nodoc:
103c254
<     def method_missing(m, *args)
---
>     def method_missing(m, *args)  # :nodoc:
109c260
<     def respond_to?(m)
---
>     def respond_to?(m)  # :nodoc:
113c264
<     def __getobj__
---
>     def __getobj__  # :nodoc:
116c267
<     def __setobj__(obj)
---
>     def __setobj__(obj)  # :nodoc:
120c271
<     def clone
---
>     def clone  # :nodoc:
124c275
<     def dup
---
>     def dup  # :nodoc:
147a299,300
> # :enddoc:
> 
Index: lib/forwardable.rb
===================================================================
RCS file: /src/ruby/lib/forwardable.rb,v
retrieving revision 1.2
diff -r1.2 forwardable.rb
0a1
> # = forwardable - Support for the Delegation Pattern
2,9c3,6
< #   forwardable.rb - 
< #   	$Release Version: 1.1$
< #   	$Revision: 1.2 $
< #   	$Date: 2001/11/03 13:41:57 $
< #   	by Keiju ISHITSUKA(keiju@ishitsuka.com)
< #	original definition by delegator.rb
< # --
< # Usage:
---
> #    $Release Version: 1.1$
> #    $Revision: 1.2 $
> #    $Date: 2001/11/03 13:41:57 $
> #    by Keiju ISHITSUKA(keiju@ishitsuka.com)
11c8,34
< #   class Foo
---
> #    Documentation by James Edward Gray II and Gavin Sinclair
> #
> # == Introduction
> #
> # This library allows you delegate method calls to an object, on a method by
> # method basis.  You can use Forwardable to setup this delegation at the class
> # level, or SingleForwardable to handle it at the object level.
> #
> # == Notes
> #
> # Be advised, RDoc will not detect delegated methods.
> #
> # <b>forwardable.rb provides single-method delegation via the
> # def_delegator() and def_delegators() methods.  For full-class
> # delegation via DelegateClass(), see delegate.rb.</b>
> #
> # == Examples
> #
> # === Forwardable
> #
> # Forwardable makes building a new class based on existing work, with a proper
> # interface, almost trivial.  We want to rely on what has come before obviously,
> # but with delegation we can take just the methods we need and even rename them
> # as appropriate.  In many cases this is preferable to inheritance, which gives
> # us the entire old interface, even if much of it isn't needed.
> #
> #   class Queue
12a36,100
> #     
> #     def initialize
> #       @q = [ ]    # prepare delegate object
> #     end
> #     
> #     # setup prefered interface, enq() and deq()...
> #     def_delegator :@q, :push, :enq
> #     def_delegator :@q, :shift, :deq
> #     
> #     # support some general Array methods that fit Queues well
> #     def_delegators :@q, :clear, :first, :push, :shift, :size
> #   end
> # 
> #   q = Queue.new
> #   q.enq 1, 2, 3, 4, 5
> #   q.push 6
> # 
> #   q.shift    # => 1
> #   while q.size > 0
> #     puts q.deq
> #   end
> # 
> #   q.enq "Ruby", "Perl", "Python"
> #   puts q.first
> #   q.clear
> #   puts q.first
> #
> # <i>Prints:</i>
> #
> #   2
> #   3
> #   4
> #   5
> #   6
> #   Ruby
> #   nil
> #
> # === SingleForwardable
> #
> #    printer = String.new
> #    printer.extend SingleForwardable        # prepare object for delegation
> #    printer.def_delegator "STDOUT", "puts"  # add delegation for STDOUT.puts()
> #    printer.puts "Howdy!"
> #
> # <i>Prints:</i>
> #
> #    Howdy!
> 
> #
> # The Forwardable module provides delegation of specified
> # methods to a designated object, using the methods #def_delegator
> # and #def_delegators.
> #
> # For example, say you have a class RecordCollection which
> # contains an array <tt>@records</tt>.  You could provide the lookup method
> # #record_number(), which simply calls #[] on the <tt>@records</tt>
> # array, like this:
> #
> #   class RecordCollection
> #     extends Forwardable
> #     def_delegator :@records, :[], :record_number
> #   end
> #
> # Further, if you wish to provide the methods #size, #<<, and #map,
> # all of which delegate to @records, this is how you can do it:
14,16c102,104
< #     def_delegators("@out", "printf", "print")
< #     def_delegators(:@in, :gets)
< #     def_delegator(:@contents, :[], "content_at")
---
> #   class RecordCollection
> #     # extends Forwardable, but we did that above
> #     def_delegators :@records, :size, :<<, :map
18,26d105
< #   f = Foo.new
< #   f.printf ...
< #   f.gets
< #   f.content_at(1)
< #
< #   g = Goo.new
< #   g.extend SingleForwardable
< #   g.def_delegator("@out", :puts)
< #   g.puts ...
27a107
> # Also see the example at forwardable.rb.
29d108
< 
33a113
>     # force Forwardable to show up in stack backtraces of delegated methods
36a117,129
>   #
>   # Shortcut for defining multiple delegator methods, but with no
>   # provision for using a different name.  The following two code
>   # samples have the same effect:
>   #
>   #   def_delegators :@records, :size, :<<, :map
>   #
>   #   def_delegator :@records, :size
>   #   def_delegator :@records, :<<
>   #   def_delegator :@records, :map
>   #
>   # See the examples at Forwardable and forwardable.rb.
>   #
42a136,142
>   #
>   # Defines a method _method_ which delegates to _obj_ (i.e. it calls
>   # the method of the same name in _obj_).  If _new_name_ is
>   # provided, it is used as the name for the delegate method.
>   #
>   # See the examples at Forwardable and forwardable.rb.
>   #
63a164,171
> #
> # The SingleForwardable module provides delegation of specified
> # methods to a designated object, using the methods #def_delegator
> # and #def_delegators.  This module is similar to Forwardable, but it works on
> # objects themselves, instead of their defining classes.
> #
> # Also see the example at forwardable.rb.
> #
64a173,185
>   #
>   # Shortcut for defining multiple delegator methods, but with no
>   # provision for using a different name.  The following two code
>   # samples have the same effect:
>   #
>   #   single_forwardable.def_delegators :@records, :size, :<<, :map
>   #
>   #   single_forwardable.def_delegator :@records, :size
>   #   single_forwardable.def_delegator :@records, :<<
>   #   single_forwardable.def_delegator :@records, :map
>   #
>   # See the example at forwardable.rb.
>   #
70a192,198
>   #
>   # Defines a method _method_ which delegates to _obj_ (i.e. it calls
>   # the method of the same name in _obj_).  If _new_name_ is
>   # provided, it is used as the name for the delegate method.
>   #
>   # See the example at forwardable.rb.
>   #

Thread

Prev Next

In This Thread

Prev Next

[#5711] Lexic confusion: method/local variable distinction works strange — noreply@...

[#5721] uninitialized constant REXML::Parsers::SAX2Parser::Text — noreply@...

[#5724] SystemExit & abort_on_exception in latest "ruby_1_8" — Johan Holmberg <holmberg@...>

[#5727] executing linux shell commands with ruby?? — Pranith Kumar Karampuri <praneeth147@...>

[#5729] Valgrind support — Tilman Sauerbeck <tilman@...>

[#5731] Ruby development issue tracking will go to basecamp — Yukihiro Matsumoto <matz@...>

[#5732] Re: Ruby development issue tracking will go to basecamp — ville.mattila@...

[#5737] returning strings from methods/instance_methods — TRANS <transfire@...>

[#5747] YAML.load hang-up — Kazuhiro NISHIYAMA <zn@...>

[#5750] File.split edge cases — "Berger, Daniel" <Daniel.Berger@...>

[#5752] assert_raises — Eric Hodel <drbrain@...7.net>

[#5753] Wilderness: AutoLoad Feature (variable.c)- Need General Description — "Charles E. Thornton" <ruby-core@...>

[#5766] Re: File.split edge cases — "Berger, Daniel" <Daniel.Berger@...>

[#5768] Wilderness: AutoLoad Feature (variable.c)- Need General Description — "Charles E. Thornton" <ruby-core@...>

[#5774] YAML broken — Kazuhiro NISHIYAMA <zn@...>

[#5779] Strange 'ambiguous arguments' warning — Nathaniel Talbott <ntalbott@...>

[#5781] array sharing — Eric Mahurin <eric_mahurin@...>

[#5784] Documentation for 1.8.3 — Eric Hodel <drbrain@...7.net>

[#5786] Difference between class declarations — Peter Vanbroekhoven <calamitas@...>

[#5787] Wilderness: How does __autoload__ work?? — "Charles E. Thornton" <ruby-core@...>

[#5793] syck.so compile error — URABE Shyouhei <s-urabe@...>

[#5796] proposed attr writer patch — Daniel Berger <Daniel.Berger@...>

[#5797] Re: proposed attr writer patch — "Berger, Daniel" <Daniel.Berger@...>

[#5798] Makefile error in OpenSLL extension (on Windows) — noreply@...

[#5804] Wilderness: Is there any way to invoke rb_define_class() from the Ruby Level — "Charles E. Thornton" <ruby-core@...>

[#5806] 5**(-1/2) gives incorrect results under mathn. — C Erler <erlercw@...>

[#5807] Wliderness: Ruby Code to force AUTOLOAD sequence to run — "Charles E. Thornton" <ruby-core@...>

[#5818] Weird SIGCHLD-related problem — Ben Schumacher <benschumacher@...>

[#5820] patch for O(1) performance for Array#unshift and Array#shift — Eric Mahurin <eric_mahurin@...>

[#5826] YAML bug - dump string terminating with ':' — "H.Yamamoto" <ocean@...2.ccsnet.ne.jp>

[#5837] Re: RubyGems in Ruby HEAD — TRANS <transfire@...>

[#5838] Re: RubyGems in Ruby HEAD — David Heinemeier Hansson <david.heinemeier@...>

[#5839] Forward: [ruby-dev:27237] Re: yaml warnig in verbose mode — nobu.nokada@...

[#5840] Re: RubyGems in Ruby HEAD — Aredridel <aredridel@...>

[#5842] Re: RubyGems in Ruby HEAD — Eric Hodel <drbrain@...7.net>

[#5844] Ruby 1.8.3 released — Yukihiro Matsumoto <matz@...>

[#5848] Re: RubyGems in Ruby HEAD — Hugh Sasse <hgs@...>

[#5851] Re: RubyGems in Ruby HEAD — Paul van Tilburg <paul@...>

[#5854] Warnings in YAML — noreply@...

[#5858] FileUtils#cd doesn't allow :noop in options anymore, but still queries it — noreply@...

[#5861] another array patch - performance boosts all over the place — Eric Mahurin <eric_mahurin@...>

[#5863] Re: another array patch - performance boosts all over the place — "Berger, Daniel" <Daniel.Berger@...>

[#5871] Wilderness: What is ID_JUNK Used for? — "Charles E. Thornton" <ruby-core@...>

[#5879] Re: RubyGems TODO — Austin Ziegler <halostatue@...>

[#5882] Re: RubyGems TODO — Austin Ziegler <halostatue@...>

[#5888] Re: RubyGems TODO — Mauricio Fern疣dez <mfp@...>

[#5896] Re: RubyGems TODO — Tom Copeland <tom@...>

[#5898] Delegate and Forwardable Documentation — James Edward Gray II <james@...>

[#5899] Re: Delegate and Forwardable Documentation — "Berger, Daniel" <Daniel.Berger@...>

[#5901] Re: RubyGems TODO — "Jim Weirich" <jim@...>

[#5902] Vulnerability fixed in 1.8.3 — Yukihiro Matsumoto <matz@...>

[#5905] The standard library "openssl" does not get built/installed in ruby 1.8.3. — noreply@...

[#5906] Re: RubyGems TODO — Daigo Moriwaki <techml@...>

[#5910] 1.8.3, pleasant surprise. — Hugh Sasse <hgs@...>

[#5921] Mutually dependent libs double loading. — TRANS <transfire@...>

[#5932] patch for imap.rb -- error handling when waiting for continuation request response — noreply@...

[#5933] — "Andreas Farre" <d00farre@...>

[#5954] FileUtils::Verbose.{compare_file,uptodate?} are private in Ruby 1.8.3 — noreply@...

[#5955] Re: RubyGems TODO (the Second) — TRANS <transfire@...>

[#5966] $SAFE=4 is still dangerous to use as a sandbox — URABE Shyouhei <s-urabe@...>

[#5970] [BUG] unknown node type 0 -- on Linux, AMD Athlon 900, Ruby 1.8.3 — noreply@...

[#5975] segmentation fault on require 'yaml' — Ralph Amissah <ralph.amissah@...>

[#5976] basecamp RSS feed requires username and passwd — sheepman <sheepman@...>

[#5984] Wilderness: How to convert from Klass/Super References to Name — "Charles E. Thornton" <ruby-core@...>

[#5985] Finally an answer to my RubyGems question and some small suggestions — TRANS <transfire@...>

[#5992] New Ruby Mirror Ready — "Scott B." <scott@...>

[#5999] ruby 1.8.3 (2005-06-23) [i486-linux] sisu segfault — Ralph Amissah <ralph.amissah@...>

[#6001] Require Namepaces and RubyGems' effect on LoadPath problem — TRANS <transfire@...>

[#6004] Problem with 1.8.3, extensions — Daniel Berger <Daniel.Berger@...>

[#6009] Re: ruby 1.8.3 (2005-09-21) [i486-linux] sisu segfault — Ralph Amissah <ralph.amissah@...>

[#6021] $\ not escaped in IO#print documentation — noreply@...

[#6031] Undefined method error in net/http.rb — noreply@...

[#6038] make warning from 1.8.3 — Daniel Berger <Daniel.Berger@...>

[#6053] _'s not escaped in Object#send documentation — noreply@...

[#6057] YAML loading of quoted Symbols broken in 1.8.3 — noreply@...

[#6070] Ads by gooooooooogle on Ruby Home Page... — Austin Ziegler <halostatue@...>

[#6076] Question about cgi.rb's read_multipart method and possible fix — "Zev Blut" <rubyzbibd@...>

[#6089] irb segfault — "David A. Black" <dblack@...>

[#6108] Re: [sydney-devel] Threading Performance? — Evan Webb <evanwebb@...>

[#6109] Fix a warning in Syck — Tilman Sauerbeck <tilman@...>

[#5787] Wilderness: How does autoload work?? — "Charles E. Thornton" <ruby-core@...>