From: Gavin Kistner <gavin@...>
Date: 2005-07-20T00:37:05+09:00
Subject: Instance Eval of a Proc

Why can I not use a Proc created from a method in #instance_eval? (Or  
rather, am I making a mistake, or is there a way to do this?)

Related: are first-class functions planned for 2.0? The whole Proc/ 
block/method situation needs unifying and simplifying, IMHO.


[Slim:~/Desktop] gavinkis% cat instance_eval_proc.rb
    class Foo
      def self.show_name( *args )
        puts "Foo.show_name says that @name is '#@name' for # 
{self.inspect}"
      end
      def initialize( name )
        @name = name
      end
    end

    f = Foo.new( "Jim" )

    my_lambda = lambda{
      puts "my_lambda says that @name is '#@name' for #{self.inspect}"
    }
    p my_lambda
    f.instance_eval( &my_lambda )

    my_proc = Proc.new{
      puts "my_proc says that @name is '#@name' for #{self.inspect}"
    }
    p my_proc
    f.instance_eval( &my_proc )

    meth_lambda = Foo.method( :show_name ).to_proc
    p meth_lambda
    f.instance_eval( &meth_lambda )


[Slim:~/Desktop] gavinkis% ruby instance_eval_proc.rb
    #<Proc:0x001ca42c@instance_eval_proc.rb:12>
    my_lambda says that @name is 'Jim' for #<Foo:0x1c9d24 @name="Jim">
    #<Proc:0x001ca10c@instance_eval_proc.rb:18>
    my_proc says that @name is 'Jim' for #<Foo:0x1c9d24 @name="Jim">
    #<Proc:0x001c9bf8@instance_eval_proc.rb:24>
    Foo.show_name says that @name is '' for Foo


[Slim:~/Desktop] gavinkis% ruby --version
    ruby 1.8.2 (2004-12-25) [powerpc-darwin8.0.0]


[Slim:~/Desktop] gavinkis% uname -a
    Darwin Slim.local 8.2.0 Darwin Kernel Version 8.2.0: Fri Jun 24  
17:46:54 PDT 2005; root:xnu-792.2.4.obj~3/RELEASE_PPC Power Macintosh  
powerpc