Data::Diver polluting $!

philkime has asked for the wisdom of the Perl Monks concerning the following question:

This snippet:

use Data::Diver qw( Dive );
my $ref = {'original' => {'default' => 'result'}};
print Dive($ref, 'original', 'default'), "\n";
die;
[download]

outputs:

result
Can't use string ("default") as a SCALAR ref while "strict refs" in use at /usr/lib/perl5/site_perl/5.14/Data/Diver.pm line 91.
        ...propagated at /tmp/test.pl line 7.

That is, simple Dive() use pollutes $! due to a test in the code. "no strict refs" doesn't fix it. It means that any die(), croak() etc. reports this even when you don't want it to. Am I missing something or perhaps there is an alternative non auto-vivifying module?

Comment on Data::Diver polluting $! Download Code

Replies are listed 'Best First'.
Re: Data::Diver polluting $! by roboticus (Chancellor) on Nov 01, 2012 at 12:23 UTC
philkime: The documentation, in the $! section, states: `$!` If used numerically, yields the current value of the C "errno" variable, or in other words, if a system or library call fails, it sets this variable. This means that *the value of $! is meaningful only immediately after a failure... A bit earlier, just after the Error Variables* heading, it mentions that: The variables `$@`, `$!`, `$^E`, and `$?` contain information about different types of error conditions ... They correspond to errors detected by the Perl interpreter, C library, operating system, or an external program, respectively. So the long and short of it is that using the value of `$!` at any time other than just after a failed operation involving the C library is a bug. ...roboticus When your only tool is a hammer, all problems look like your thumb.	[reply] [d/l] [select]
Re: Data::Diver polluting $@ by Anonymous Monk on Nov 01, 2012 at 10:49 UTC
No, Data::Diver is not polluting $@ Don't use die like that, give die an argument or use exit	[reply]
Re^2: Data::Diver polluting $@ (local) by tye (Sage) on Nov 01, 2012 at 13:35 UTC
Although I mostly agree, I'll try to upload a new release of Data::Diver in short order that adds `local($@)` any places that it uses eval. And thanks for mentioning `$@` as it saved me from figuring out what was really going on, because I was immediately pretty sure that the problem wasn't with `$!`, but I didn't immediately realize what the real problem was. - tye	[reply] [d/l] [select]
Re^3: Data::Diver polluting $@ (truth) by Anonymous Monk on Sep 26, 2015 at 00:04 UTC
Here is another, docs lead me to believe these should all work but Dive doesn't `#!/usr/bin/perl -- use strict; use warnings; use Data::Diver qw/ Dive DiveRef DiveDie /; sub say { print @_, "\n"; } say DiveDie( DiveRef( { qw/ key val / }, \'key' ) ); say DiveDie( Dive( { qw/ key val / }, \'key' ) ); __END__ SCALAR(0x3f90cc) Key not present in hash using SCALAR(0xabe37c) on HASH(0x3f90dc) (from + Data::Diver).` [download] Problem is in sub Dive, when you're testing if $ref is a hash with eval, you forgot the 1, this line - `} elsif( eval { exists $ref->{$key} } ) {` + `} elsif( eval { exists $ref->{$key}; 1 } ) {` I've tested it it works , your test suite doesn't test for this so maybe add to Data-Diver-1.0101/t/base.t the following `ok( 'val', Dive( { qw/ key val / }, \'key' ) ); ok( 'val', Dive( { qw/ key val / }, 'key' ) ); ok( 'val', DiveVal( { qw/ key val / }, \'key' ) ); ok( 'val', DiveVal( { qw/ key val / }, 'key' ) );` [download] Also remember the Replacment for Data::Diver due missing license For the honor	[reply] [d/l] [select]


good chemistry is complicated, and a little bit messy -LW
	PerlMonks