From: "David A. Black" <dblack@...>
Date: 2005-11-07T12:18:27+09:00
Subject: Re: programming best practices

Hi --

On Mon, 7 Nov 2005, swille wrote:

> I have a couple of standard programming questions.  The first is that
> I often like to return true or false in a method when no other return
> value is really needed.  Is that bad form?  I was talking to someone
> the other day who said said something that made me think that maybe it
> was.  For example:
>
> def login()
>    rc = false
>    begin
>         perform action
>    rescue
>        rc = false
>        some error
>    end
>
>    return rc
> end
>
> I like that because it reads well when you use it
>
> if login
>    do_stuff
> else
>    complain
> end

But the way you've written it, rc is always false.  Did you mean true
in the first line? :-)

Also, it seems a little bit like you've got two error-reporting
systems going on.  Maybe you could combine them:

   def login
     perform action
   end

   begin
     login
   rescue
     ...
   end

etc.

> My second question is this.  I occasionally see stuff like
> if -1 == result
>
> rather than
> if result == -1
>
> What, if any, is the benefit of one over the other?

As another answerer said, the first one (if -1 == result) protects you
from accidentally writing = instead of ==.  In Ruby it's less of an
issue than in other languages because you'll get a warning:

   if a = 1; end
   (irb):1: warning: found = in conditional, should be ==

It's considered worthy of warning because there would never be any
"if" about a case like this: 1 is true, so the expression "a = 1" is
true.

The cool thing about this is that you *don't* get the warning when you
might actually want to do it:

   b = 1
   if a = b  # no warning


David

-- 
David A. Black
dblack@wobblini.net