If I do not explicitly want a specific initial value for a variable, I purposely leave it undefined so that I get a warning if I use it before I was planning to.

If I do not want an explicit initial value for a variable, I tend to set it explicitly to undef. It tends to pair up well with a latter test for definedness, and it also shows that I have considered that the variable containing an undefined value is actually, er, defined behaviour. Consider the snippet:

my $key = undef;
for my $k( keys %h ) {
  $key = $k if $h{$k} eq 'foo';
}
if( defined $key ) {
  # ...
}
[download]

I find it makes it clearer to see that the variable starts out undefined and that the loop could set the variable to some value.

print@_{sort keys %_},$/if%_=split//,'= & *a?b:e\f/h^h!j+n,o@o;r$s-t%t#u'

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