Re: Variable Naming

Here is a example of trying to learn from our betters and getting confused. The node Randal does it again refers to an article by Randal Schwartz.

I found this snippet of code that uses a variable name $old_flag.

sub wanted {
  return unless -f $_;
  my $old_flag = -M $_ > 180 ? 'old' : 'new';
  $ages{$File::Find::dir}{$old_flag}++;
}
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My confusion arises because I would have expected $old_flag to hold a true/false value. Shouldn't this variable be named something like $age_status. This would make it "sound" better to say : $age_status is new or old.

How should this be handled?

Comment on Re: Variable Naming Download Code

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Re: Re: Variable Naming
by rir (Vicar) on Sep 27, 2002 at 20:59 UTC

sub wanted {
  return unless -f $_;
  my $old_flag = -M $_ > 180 ? 'old' : 'new';
  $ages{$File::Find::dir}{$old_flag}++;
}
[download]

Likely this is in a little script and I'd have no
complaint

There is certainly a trap of believing variable names.
Like believing the documentation.

This looks like code that was refactored because the
routine name also seems to reflect a time when the author
was going to use a boolean return here and effect his count
elsewhere.

If this was part of a larger body of code...
My first concerns, assuming it does what is wanted, are:

Is 180 magic?
Where did %ages come from?
Are 'old' and 'new' magical, Hash keys can be a difficult call on magicalness.
Is the routine name okay. Maybe a leading underscore.

The $old_flag might make my list, a meaningless name like
$var seems better. But it is an issue for only two lines.

I would consider inlining:

# untested
if ( -f $file) {
   $age{$File::Find::dir}{ -M $file < 180 ? 'old' : 'new' }++;
}
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