From: Dave Burt <dave@...>
Date: 2006-05-21T08:56:24+09:00
Subject: Re: I call Ducktype Violation on #to_proc! :)

Daniel Schierbeck wrote:
>   class CachedProc
>     def initialize(&proc)
>       @proc = proc
>       @cache = Hash.new{|cache, args| cache[args] = @proc.call(*args)}
>     end
> 
>     def call(*args)
>       @cache[args]
>     end
> 
>     alias_method :[], :call
> 
>     def to_proc
>       # must return a Proc...
>       @proc
>     end
> ...
> This is fine and all, but doesn't work with iterators and such:
> 
>   proc = cached_proc{|obj| expensive_operation(obj)}
>   [2, 5, 7, 4, 2, 8, 2].collect(&proc)
> 
> Here, the caching doesn't work, because the CachedProc is converted to a
> Proc.

def to_proc
  proc {|*args| self.call(*args) }
end

Cheers,
Dave