Re: I can't see why this shorthand doesn't behave like the verbose form

@Ken: I think you are right - it's time to look at JSON and SQL.

Today I've found the time to hack together a simple test script that doesn't exhibit the original problem. Here, when the variable is properly declared (or not) and populated in perl context, shorthand and longform behave the same.

Also, I've removed the noise of the eval and the defined() check, the latter I threw in anyway down the road when the simple check didn't seem to suffice.

In my production code the related_files data comes from a SQL field that is parsed based on the test if($sql->{field}), so I think that there's a slight difference how perl regards this field as defined, existing or true. But I am not so inclined to find out why exactly the shorthand doesn't work. As the more verbose code just works. Also, might also be an unrelated error I am overseeing. I'll post if there's a find in the future.

#! perl

use Data::Dumper;
use JSON::XS;

my $asset = {
        ## rename this var to something else to test the 'undefined' c
+ase
        related_files => '{
     "firstName": "John",
     "lastName" : "Smith",
     "age"      : 25,
     "address"  :
     {
         "streetAddress": "21 2nd Street",
         "city"         : "New York",
         "state"        : "NY",
         "postalCode"   : "10021"
     },
     "phoneNumber":
     [
         {
           "type"  : "home",
           "number": "212 555-1234"
         },
         {
           "type"  : "fax",
           "number": "646 555-4567"
         }
     ]
 }'
};



my $ref;
if($asset->{related_files}){
 $ref = decode_json($asset->{related_files});
}else{
 $ref = [];
}

print Dumper($ref);

## simpler shorthand-code doesn't work, why?
my $ref = $asset->{related_files} ? decode_json($asset->{related_files
+}) : [];

print Dumper($ref);
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Re^2: I can't see why this shorthand doesn't behave like the verbose form by tobyink (Canon) on Mar 25, 2012 at 14:52 UTC
Really? Your script works as expected on this machine. I suppose you might have a severely broken JSON::XS - that's the only place I can see it possibly breaking. Tried JSON::PP? `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply]
Re^2: I can't see why this shorthand doesn't behave like the verbose form by Anonymous Monk on Mar 25, 2012 at 14:26 UTC
Here is a demonstration of it working, and some alternatives :) #!/usr/bin/perl -- use strict; use warnings; use Data::Dump; use JSON::XS; my $ref = { foo => q{[1,2,3]} }; for my $key( qw/ bar foo /) { { my $foo; if( $ref->{$key} ){ $foo = decode_json( $ref->{$key} ); } else { $foo = []; } dd $foo; } { my $foo = []; if( $ref->{$key} ){ $foo = decode_json( $ref->{$key} ); } dd $foo; } { my $foo = $ref->{$key} ? decode_json( $ref->{$key} ) : []; dd $foo; } { my $foo = eval { decode_json( $ref->{$key} ) } \|\| []; dd $foo; } } __END__ [] [] [] [] [1, 2, 3] [1, 2, 3] [1, 2, 3] [1, 2, 3] [download]	[reply] [d/l]