http://www.perlmonks.org?node_id=576669


in reply to Bad return value from a block with variable localization

From this site, first posted on March 28, 2006:
[Please enter your report here] Hello, I've run into this strange behaviour when playing with trying to make functions return different values from the number of parameters they were called with. If you test [at]_, and that you return from a do { ... } block where a variable is localized, the return value is undef if you don't add an else statement. Looks like some parsing bug, but not that I'm good enough to have any real clue about it. Regards, Vincent Pit ################################################################# Test case: (line 1 is #!) #!/usr/bin/perl use strict; use warnings; sub foo { if (@_) { return do { my $dummy; 1; }; } else { return 0; } } # let's just remove the else sub bar { if (@_) { return do { my $dummy; 1; }; } return 0; } print foo().' '.foo('baz')."\n"; # that was expected print bar().' '.bar('baz')."\n"; # undef ################################################################# Expected output: 0 1 0 1 ################################################################# Actual output: 0 1 Use of uninitialized value in concatenation (.) or string at ./bug.pl +line 24. 0 #################################################################

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