From: transfire@...
Date: 2006-06-15T04:27:15+09:00
Subject: Re: Why the lack of mixing-in support for Class methods?


Joel VanderWerf wrote:

> Why should the order of calling extend and adding methods matter? It
> doesn't seem to in this example, but this is much simpler than
> class_extension:

It's a little more subtle than that, because it has to do with modules
included in modules.

irb(main):001:0> module M
irb(main):002:1>   def foo; p "FOO"; end
irb(main):003:1> end
=> nil
irb(main):004:0> module N
irb(main):005:1>   def bar; p "BAR"; end
irb(main):006:1> end
=> nil
irb(main):007:0> module O
irb(main):008:1>   def baz; p "BAZ"; end
irb(main):009:1> end
=> nil
irb(main):010:0> module M
irb(main):011:1>   include N
irb(main):012:1> end
=> M
irb(main):013:0> class C
irb(main):014:1>   extend M
irb(main):015:1> end
=> C
irb(main):016:0> C.foo
"FOO"
=> nil
irb(main):017:0> C.bar
"BAR"
=> nil
irb(main):018:0> module M
irb(main):019:1>   include O
irb(main):020:1> end
=> M
irb(main):021:0> C.baz
NoMethodError: undefined method `baz' for C:Class
        from (irb):21
        from :0

T.