From: Florian Gross <flgr@...>
Date: 2004-12-09T09:32:31+09:00
Subject: Re: [ANN] Ruby/Extensions v0.6.0

Gavin Sinclair wrote:

> On Thursday, December 9, 2004, 6:57:28 AM, Florian wrote:
>>Thanks, I was fearing that there would be name clashes with the 
>>Ruby-Junction library which defines Enumerable#none, #any, #all, 
>>#with_count and #exactly.
> You might be interested to know that 'extensions' is careful about
> adding methods.  If, for example, you did this:
> 
>   class Array; def rand; ...; end; end
> 
>   require 'extensions/array'
> 
> then you'd get a warning on STDERR, something like
> 
>   WARNING: Array#rand exists, not overwriting

Oh, that's quite a nifty feature. Well done!

>>Array#rand sounds interesting, but I wonder if it does not lead to 
>>trouble when using rand() from a custom overloaded Array or Enumerable
>>method.
> What might an example of this trouble be?  For a start, it's only
> defined on Array, not Enumerable.  And its definition is very simple:
> 
>   def rand
>     idx = Kernel.rand(self.size)
>     at(idx)
>   end
> 
> So any array that properly implements size and at should do the trick.

I'm thinking about something like this: (Made-up sample, does not make 
much sense in isolation -- but it could also happen in real code.)

class Enumerable
   def find_some(chance = 0.5)
     find_all { rand < chance }
   end
end

I think using the Array#rand extension would lead to trouble in this case:

[1, 2, 3].find_some

Because Enumerable#find_some expects to call Kernel#rand.

I'm not sure if it is necessary to rename it (Array#pick_rand seems to 
be a common candidate), but a note in the documentation might be a good 
thing.

> BTW Florian, while I've got you on this subject, I must apologise for
> an incorrect attribution in extensions: Florian Frank appears in there
> on one occasion instead of you.  FINR :)

Oh, no problem there -- we tend to get confused a lot. I guess one could 
refer to me as 'flgr' instead in case it would help.