I recently read this page on mysql gotchas and worried. I was glad that perl did not have this sort of gotcha.

Then I read About variable names and got worried again.

This morning I was burnt by this gotcha (code has been simplified): 

use strict;                      # line 1
use warnings;                    # line 2
                                 # line 3
my $value1 = 'foo';              # line 4
my $value2 = undef;              # line 5
                                 # line 6
if ( $value1 eq 'bar' ) {        # line 7
  print 'value1 is bar';         # line 8
                                 # line 9
} elsif ( $value2 eq 'bar' ) {   # line 10
  print 'value2 is bar';         # line 11
                                 # line 12
}                                # line 13

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Because when you run it you get this from the warnings: 
[evdb@desktop evdb]$ perl test.pl 
Use of uninitialized value in string eq at test.pl line 7.

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But the 'undef in string eq' is on line 10! ( This took quite a while to debug ).

I ask you, what other perl gotchas are there out there that could bite me?

PS: I've looked at Regular Expression gotchas, Common Regex Gotchas and others from seaching for 'gotcha'.

--tidiness is the memory loss of environmental mnemonics

In reply to Perl Gotchas. by EvdB

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