From: Hal Fulton <hal9000@...>
Date: 2004-11-12T10:17:15+09:00
Subject: Re: non-nil, etc.  (was Re: true? & false?)

trans. (T. Onoma) wrote:
> On Thursday 11 November 2004 07:30 pm, Gavin Sinclair wrote:
> | Smiley shmiley:
> |
> |   require 'extensions/object'
> |
> |   if a.notnil?
> |     ...
> |   elsif b.nonnil?
> |     ...
> |   end
> 
> What's wrong with:
> 
>    if not a.nil?
>      ...
>    end

Nothing, really. I'd ordinarily use that, especially in public.

It's a minor bit of (my personal) psychology, really. I'd rather
ask what something IS rather than what it ISN'T.

In the same way, we could say and 'if not a' -- but there is
something a little clearer about 'a.nil?' instead.

It's (distantly) like the line of code I wrote which said:

   upload unless unchanged

and people commented, Why wouldn't you say:

   upload if changed

And I could really only say: Well, that's how I think.

When I code an if, I usually code the "expected" or "normal" case
as the first branch, and the rest as the "else" part.

Similarly when I use unless, it's usually when a case is (expected
to be) rare or exceptional.

Because the file would "normally" be changed, the "unless" part was
an exception to the rule.

This is that kind of thing. It's all in my head.


Hal