-- Yehuda

On Sun, Jan 18, 2009 at 1= 0:04 PM, Tomas Matousek <Tomas.Matousek@microsoft.com> wrote:

I believe that methods (a= nd blocks defined as methods via method_defined) are somehow closed over the module that declares them so th= at "super" can find the right module/class whose parent's method to call. At least they are in IronRuby J

A simple copy of a method= without changing binding to its declaring module therefore causes super to fail (or changes its semantics). I think t= his is the case even for module_function (I might have an example somewhere tha= t demonstrates it, will send it tomorrow if I find it). module_function "copies" the method from declaring module to its singleton class, which is indeed no= t derived from the declaring module, breaking super in some constructed cases.=

Tomas

From: Yehuda Katz [mailto:wycats@gmail.= com]
Sent: Sunday, January 18, 2009 3:14 PM
To: rub= y-core@ruby-lang.org
Subject: [ruby-core:21423] Re: Proposal: Module#copy_method

Just FYI, the define_method version fails if your method requires the use of super. Observe:

class Zoo1
def bar
    p "In superclass"
    1
end
end

class Zoo2 < Zoo1
def bar
    p "in Zoo2mod #{self}"
    super + 1
end

mod =3D Module.new do
    define_method(:bar, Zoo2.instance_method(:bar))
end
include mod

def bar
    p "In bar"
    super + 1
end
end

p Zoo2.new.bar

The above produces SystemStackError: stack level too deep, infinite-looping= in the original bar implementation on Zoo2. Also, it doesn't work on 1.9.<= br>
-- Yehuda

On Sun, Jan 18, 2009 at 2:32 PM, Charles Oliver Nutter <charles.nutter@sun.com&g= t; wrote:

Yehuda Katz wrote:

I'd like it to be possible to copy methods from one module to another. The rationale is that this feature would make it possible to mo= dify existing methods without being forced to resort to aliasing. Here's an implementation that works on 1.8 and 1.9:

Here's a pure-ruby version that works on an unmodified JRuby:

require 'jruby'

class Module
def copy_method(mod, sym)
# get JRuby DynamicMethod object from RubyMethod
org.jruby.RubyMethod.field_reader :method
ruby_method =3D mod.instance_method(sym)
real_method =3D JRuby.reference(ruby_method).method

# native methods may have memory/object layout needs
raise "can't copy native method" if real_method.= native?

# Add it directly to the JRuby RubyModule self
real_modcls =3D JRuby.reference(self)
real_modcls.add_method(sym.to_s, real_method)
end
end

- Charlie

--
Yehuda Katz
Developer | Engine Yard
(ph) 718.877.1325

--
Yehuda Katz
Develope= r | Engine Yard
(ph) 718.877.1325

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