Sprad has asked for the wisdom of the Perl Monks concerning the following question:
Observing a hash changes its contents...
I'm using a hash of hashes, and doing an existence check. If the check fails, I print a usage giving the valid keys. Strangely, the invalid key is being created by the existence check. I added a line to delete it, which fixes it, but why is this happening at all?
Here's a sample repro:
'd' appears in the output list. No change if I use defined() for the exist check.#!/usr/bin/perl -w use strict; my %hash = ('a' => { 'value' => 1, 'foo' => 'bar', }, 'b' => { 'value' => 2, 'foo' => 'bar', }, 'c' => { 'value' => 3, 'foo' => 'bar', }, ); if (! $hash{'d'}->{'value'}) { print "That key doesn't exist. Valid keys are: "; print join (", ", keys %hash); }
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A fair fight is a sign of poor planning.
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Re: Heisenberg Uncertainty Hash
by japhy (Canon) on Apr 26, 2005 at 22:48 UTC | |
by DrHyde (Prior) on Apr 27, 2005 at 08:50 UTC | |
by Anonymous Monk on Apr 27, 2005 at 09:04 UTC | |
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Re: Heisenberg Uncertainty Hash
by Zaxo (Archbishop) on Apr 26, 2005 at 22:50 UTC | |
Re: Heisenberg Uncertainty Hash
by ikegami (Patriarch) on Apr 26, 2005 at 22:51 UTC | |
Re: Heisenberg Uncertainty Hash
by Roy Johnson (Monsignor) on Apr 27, 2005 at 04:30 UTC | |
Re: Heisenberg Uncertainty Hash
by tlm (Prior) on Apr 27, 2005 at 00:12 UTC | |
OT: Heisenberg Uncertainty link
by inman (Curate) on Apr 27, 2005 at 09:40 UTC |
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