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Posted by Jeff Boes on March 8, 2005, 1:08 pm
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I need a module that will support this behavior:
use strict;
my %hash = ('A' => 1, 'B' => 2);
eval { my $x = $hash; # reference to non-existing hash element! };
# At this point, $EVAL_ERROR should be set to some error message!
I think I can write this up using Tie::Hash, but I'm hoping it's already
done. CPAN was no help, mostly because I can't come up with a good
search string that would narrow down my requirements.
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Posted by Gunnar Hjalmarsson on March 8, 2005, 10:50 pm
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Jeff Boes wrote:
> I need a module that will support this behavior:
>
> use strict;
> my %hash = ('A' => 1, 'B' => 2);
>
> eval { my $x = $hash; # reference to non-existing hash element! };
>
> # At this point, $EVAL_ERROR should be set to some error message!
Leaving the syntax error aside, how would eval() catch an error?
Assigning the undefined value to a variable is not wrong.
And why would you need a module? Can't you just do something like:
defined ( my $x = $hash ) or warn 'Undefined %hash value';
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
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Posted by Jim Gibson on March 8, 2005, 2:54 pm
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> Jeff Boes wrote:
> > I need a module that will support this behavior:
> >
> > use strict;
> > my %hash = ('A' => 1, 'B' => 2);
> >
> > eval { my $x = $hash; # reference to non-existing hash element! };
> >
> > # At this point, $EVAL_ERROR should be set to some error message!
>
> Leaving the syntax error aside, how would eval() catch an error?
> Assigning the undefined value to a variable is not wrong.
>
> And why would you need a module? Can't you just do something like:
>
> defined ( my $x = $hash ) or warn 'Undefined %hash value';
Or, if the question is whether or not the hash element with key C had
ever been assigned a value (even the undef value):
exists ( $hash ) or warn 'Non-existent %hash value';
Note you can't assign to $x here because exists needs a hash or array
element.
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Posted by Slaven Rezic on March 8, 2005, 11:50 pm
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> I need a module that will support this behavior:
>
> use strict;
> my %hash = ('A' => 1, 'B' => 2);
>
> eval { my $x = $hash; # reference to non-existing hash element! };
>
> # At this point, $EVAL_ERROR should be set to some error message!
>
> I think I can write this up using Tie::Hash, but I'm hoping it's
> already done. CPAN was no help, mostly because I can't come up with a
> good search string that would narrow down my requirements.
Try the lock_keys function from the standard Hash::Util module.
Regards,
Slaven
--
Slaven Rezic - slaven <at> rezic <dot> de
tknotes - A knotes clone, written in Perl/Tk.
http://ptktools.sourceforge.net/#tknotes
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Posted by Jeff Boes on March 9, 2005, 8:49 am
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>> eval { my $x = $hash; # reference to non-existing hash element! };
>>
>> # At this point, $EVAL_ERROR should be set to some error message!
>>
>
>Try the lock_keys function from the standard Hash::Util module.
>
Just what I was looking for! Thanks!
--
~~~~~~~~~~~~~~~~| Genius may have its limitations, but stupidity is not
Jeff Boes | thus handicapped.
jboes@qtm.net | --Elbert Hubbard (1856-1915), American author
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