From: Robert Klemme <bob.news@...>
Date: 2004-01-15T18:11:36+09:00
Subject: Re: Warnings on assignments in conditionals?


"Bret Jolly" <oinkoink+unet@rexx.com> schrieb im Newsbeitrag
news:7e7131a1.0401141110.d5fa65a@posting.google.com...
> David Heinemeier Hansson <david@loudthinking.com> wrote in message
news:<8609BD15-45EF-11D8-A416-000A958E6254@loudthinking.com>...
> > I consider the following statements to be perfectly legit (although
> > perhaps slightly ambigious) and Ruby does obey, but throws this
> > mandating warning. Am I just being paranoid or is Ruby forcing a style
> > upon me :)?
> >
> > irb(main):008:0> if a = 1 then true else false end
> > (irb):8: warning: found = in conditional, should be ==
> > => true
> > irb(main):009:0> a
> > => 1
> >
> > irb(main):010:0> if a = nil then true else false end
> > (irb):10: warning: found = in conditional, should be ==
> > => false
> > irb(main):011:0> a
> > => nil
>
>   But this C idiom really doesn't make much sense in Ruby, since
> in Ruby 0 is true in a boolean context.  You might want to say
> something like:
>           if not (a = c).nil? then foo else bar end
> but what you have is almost certainly either an error or at least
> stylistically dubious. So yes, I guess Ruby is forcing a style on
> you.  I think that if you really want something like this, the Ruby
> way would be to define a method 'true?' for objects:
> class Object
>  def true?
>    if nil? or self == false then return false end
>    true
>  end
>  def false?
>    not true?
>  end
> end
>
> then write:
>        if  (a = c).true? then foo else bar end

*shudder*  You're not serious, are you?  And if so, why didn't you define
them like this:

class Object
  def true?; self; end
  def false?; not self; end
end

Cheers

    robert