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comp.lang.ruby

aliasing an external method from within a method definition?

Francis Hwang

3/7/2005 7:04:00 AM

So maybe some of you language wizards out there can help me with this:
Is there a way to define a method that aliases some external method
without assigning that method to a global in the first place?

The example is the code below: For mockfs/override.rb, I'm undefining
File, but want to keep File.join.

$join_method = File.method :join
Object.send( :remove_const, :File )
module File
def self.join( *args )
$join_method.call *args
end

def self.method_missing( symbol, *args )
MockFS.file.send( symbol, *args )
end
end

This works, but then I'm leaving a global variable just sitting around.
Is there a better way to do this?

Francis Hwang
http://f...
4 Answers

Joel VanderWerf

3/7/2005 7:29:00 AM

0

Francis Hwang wrote:
> So maybe some of you language wizards out there can help me with this:
> Is there a way to define a method that aliases some external method
> without assigning that method to a global in the first place?
>
> The example is the code below: For mockfs/override.rb, I'm undefining
> File, but want to keep File.join.
>
> $join_method = File.method :join
> Object.send( :remove_const, :File )
> module File
> def self.join( *args )
> $join_method.call *args
> end
>
> def self.method_missing( symbol, *args )
> MockFS.file.send( symbol, *args )
> end
> end
>
> This works, but then I'm leaving a global variable just sitting around.
> Is there a better way to do this?

I'll be the firstest with the worstest:

x = 1
M = Module.new do
(class << self; self; end).instance_eval do
define_method :foo do
x
end
end
end

p M.foo # ==> 1

Mutatis mutandis.

Luke Graham

3/7/2005 7:32:00 AM

0

On Mon, 7 Mar 2005 16:03:40 +0900, Francis Hwang <sera@fhwang.net> wrote:
> So maybe some of you language wizards out there can help me with this:
> Is there a way to define a method that aliases some external method
> without assigning that method to a global in the first place?
>
> The example is the code below: For mockfs/override.rb, I'm undefining
> File, but want to keep File.join.
>
> $join_method = File.method :join
> Object.send( :remove_const, :File )
> module File
> def self.join( *args )
> $join_method.call *args
> end
>
> def self.method_missing( symbol, *args )
> MockFS.file.send( symbol, *args )
> end
> end
>
> This works, but then I'm leaving a global variable just sitting around.
> Is there a better way to do this?

Im a long way from a wizard, but how about this...

OldFile = File.clone
Object.send :remove_const, :File
module File
OldFile = OldFile.clone
def self.method_missing(symbol, *args)
File.send symbol, *args
end
end


--
spooq

Luke Graham

3/7/2005 7:35:00 AM

0

On Mon, 7 Mar 2005 17:31:24 +1000, Luke Graham <spoooq@gmail.com> wrote:
> On Mon, 7 Mar 2005 16:03:40 +0900, Francis Hwang <sera@fhwang.net> wrote:
> > So maybe some of you language wizards out there can help me with this:
> > Is there a way to define a method that aliases some external method
> > without assigning that method to a global in the first place?
> >
> > The example is the code below: For mockfs/override.rb, I'm undefining
> > File, but want to keep File.join.
> >
> > $join_method = File.method :join
> > Object.send( :remove_const, :File )
> > module File
> > def self.join( *args )
> > $join_method.call *args
> > end
> >
> > def self.method_missing( symbol, *args )
> > MockFS.file.send( symbol, *args )
> > end
> > end
> >
> > This works, but then I'm leaving a global variable just sitting around.
> > Is there a better way to do this?
>
> Im a long way from a wizard, but how about this...
>
> OldFile = File.clone
> Object.send :remove_const, :File
> module File
> OldFile = OldFile.clone
> def self.method_missing(symbol, *args)
> File.send symbol, *args
> end
> end

Missed the final..

Object.send :remove_const, :OldFile

Better name the OldFile in the module something different too :P

--
spooq

Pit Capitain

3/8/2005 8:46:00 AM

0

Francis Hwang schrieb:
> Is there a way to define a method that aliases some external method
> without assigning that method to a global in the first place?
> ...
> This works, but then I'm leaving a global variable just sitting around.
> Is there a better way to do this?

If you don't mind a local variable then this might help:

m = Module.new

class << m
define_method(:join, &File.method(:join))
def method_missing(*args)
args
end
end

Object.send(:remove_const, :File)
File = m

p File.join("a", "b") # => "a/b"
p File.open("x", "y", "z") # => [:open, "x", "y", "z"]

Regards,
Pit