From: ptkwt@... (Phil Tomson)
Date: 2004-01-20T13:39:58+09:00
Subject: Re: RCR discussion: safety considerations

In article <20040119091022.GA1193@student.ei.uni-stuttgart.de>,
Mauricio Fern�ndez  <batsman.geo@yahoo.com> wrote:
>On Mon, Jan 19, 2004 at 01:25:01PM +0900, Phil Tomson wrote:
>> Another issue that was raised was that Ruby doesn't have effective methods 
>> (or at least not as effective as other languages have) of avoiding 
>> namespace collisions.  For example, when we 'include' a module we get all 
>> of the methods in that module imported into the current 
>> namespace.  What if we could optionally list the methods/classes we want 
>> to include, similar to Python's import:
>> 
>>   import Blah func1,func2,MyClass
>
>IMHO this handles a pretty benign issue, as methods in the current class
>will be preferred to those of a mix-in. It does nothing to solve the
>following, however:
>
>module Bar  # idiotic code
>	def foo
>		1 + bar(1, 2, 3)
>	end
>	def bar(*a)
>		1
>	end
>end
>
>class Foo
>	include Bar # , :foo 
>	def bar  # changing the interface
>		"bla"
>	end
>end
>
>Foo.new.foo  # booboo
>
>And in the following case...
>module Foo
>	def foo; ...;  bar; ...;  end
>	def bar; ... end
>end
>module Bar
>	def bar; ... end
>end
>class A
>	include Bar
>	include Foo, :foo   # bar too?
>end
>
>> This imports the methods func1 and func2 and the class MyClass from Blah.  
>> Perhaps similar options could be added to 'require'.
>
>I cannot think of any meaningful semantics for require 'foo', :blah.
>
>> Thoughts?  Is this necessary?  Is it advisable?
>
>What problem does  include Bar, :bla  solve in addition to 'feature
>deficit'? 


Perhaps you're right.  Being able to pick & choose what methods to include 
from a module probably isn't all that useful.  If you're worried about 
namespace collisions you can always do:
  ModuleName::func

Also, people tend to include instance variables in Modules and if you 
don't include the module's 'constructor' you may not set these up 
correctly.

Anyway, since this hasn't turned into an active thread I would tend to 
think that most people just don't see the need, so I probably won't file 
any RCRs in this area.

....Though the freeze levels idea might be worthy of an RCR.


Phil