in reply to Variable Naming
in thread Tact and the Monastery

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?

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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}++;
}

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    Likely this is in a little script and I'd have no
    complaint     with its expeditious style. Something of the
    thank-goodness-I-got-it-to-work style with which I am quite
    familiar.

    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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