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gav (2710)

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Hacker in NYC.

Journal of gav (2710)

Wednesday July 14, 2004
02:37 PM

Pointless temporary variables

[ #19852 ]

One of my pet peeves is pointless temporary variables, they often just clutter things up. Consider this example (pulled from production code) that is crying out for some refactoring.

my $keywords;
@$keywords = split ' ', $something;
foreach my $word (@$keywords) {
    # ...


foreach my $word (split ' ', $something) {
    # ...

Isn't this much easier to understand?

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  • the original author wanted to be able to view @$keywords in a debugger, to see the result of the split.

    I've split up operations sometimes, placing an intermediary step in between, to facilitate debugging.

    Just a thought.
  • Both examples make sense to me, but if you've got Perl coders who don't code Perl *all* the time, I think the second example would require a few more brain cycles than the the first. This is especially true if there's one part they don't remember--like the fact that split returns a list. The temporary variable re-enforces this by showing it. Besides, memory is cheap :)
  • Folks advocate well named temp variables for clarity, similar to well named functions. Its not obvious from glancing at just a split that you're getting a list of keywords. It is obvious from "my @keywords = split ...". However, "foreach my $keyword (split ...)" works just as well.

    I have seen this concept abused.

    sub foo {
        my $thing = shift;
        my $foo = ...some simple calc...;
        return $foo;

    Other times folks start out with the long hand version using temp variables