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Top Forums Programming Perl: restrict perl from automaticaly creating a hash branches on check Post 302924341 by durden_tyler on Saturday 8th of November 2014 02:12:18 AM
Old 11-08-2014
That's a documented behavior in Perl and is called "autovivification".
Check the stackoverflow website for the question "How do I disable autovivification in Perl?" for a detailed discussion and workarounds.

gandolf989 has a point here. Any reason you do *not* want the intermediate branches to be created? As long as they are empty and your existence checks return the values as expected, your program should be fine.

Autovivification in Perl is by design. It's not a bug; it's a feature. And I think it stems from Perl's tendency to go out of its way to make your text processing task easy.
For an in-depth technical discussion of why it works like that, what its advantages are and what problems it solves, check this link: http://www.sysarch.com/Perl/autoviv.txt
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PAR::Filter::Bytecode(3)				User Contributed Perl Documentation				  PAR::Filter::Bytecode(3)

NAME
PAR::Filter::Bytecode - Bytecode filter SYNOPSIS
PAR::Filter::Bytecode->apply($code); # transforms $code DESCRIPTION
This filter is deprecated. The B::Bytecode code has been removed from the newest development series of perl and will not be included in perl 5.10 any more. Please have a look at Steve Hay's PAR::Filter::Crypto module if you want to hide your sources. This filter uses B::Bytecode to turn the script into comment-free, architecture-specific Perl bytecode, and uses ByteLoader to load back on execution. For pp users, please add an extra -M option, like this: pp -f Bytecode -M ByteLoader Otherwise, the implicit dependency on ByteLoader will not be detected. CAVEATS
This backend exhibits all bugs listed in B::Bytecode, and then some. Bytecode support is considered to be extremely fragile on Perl versions earlier than 5.8.1, and is still far from robust (as of this writing). Bytecode is not supported by perl 5.9 and later. SEE ALSO
PAR::Filter, B::Bytecode, ByteLoader Filter::Crypto, PAR::Filter::Crypto AUTHORS
Audrey Tang <cpan@audreyt.org> <http://par.perl.org/> is the official PAR website. You can write to the mailing list at <par@perl.org>, or send an empty mail to <par-subscribe@perl.org> to participate in the discussion. Please submit bug reports to <bug-par@rt.cpan.org>. COPYRIGHT
Copyright 2003-2009 by Audrey Tang <cpan@audreyt.org>. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See <http://www.perl.com/perl/misc/Artistic.html> perl v5.18.2 2012-01-06 PAR::Filter::Bytecode(3)
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