Re: Autovivification identification

Perl knows what you want to do, because that is what you have asked it to do:

# You use push so you must want an array
push @{ $provisions{$person} }, $1; 

# You use hash of hash addressing so you must want a hash
$total_bytes{$source}{$destination} += $bytes;
[download]

The programmer has made the decision based on the data structure thought to be most useful in each case.

You can make it as crazy as you like and Perl will obey...

perl -MData::Dumper -le'$t{x}{y}[2]{foo}[3]{bar}=1; print Dumper \%t'
$VAR1 = {
          'x' => {
                   'y' => [
                            undef,
                            undef,
                            {
                              'foo' => [
                                         undef,
                                         undef,
                                         undef,
                                         {
                                           'bar' => 1
                                         }
                                       ]
                            }
                          ]
                 }
        };
[download]

Cheers,
R.

Pereant, qui ante nos nostra dixerunt!

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Re^2: Autovivification identification by choroba (Cardinal) on Aug 01, 2013 at 09:42 UTC
Note that in recent Perl (since 5.14), push can take an array reference as the first argument. This is an experimental feature and no autovivification happens here: `my $x = []; push $x, 0, 1, 2; # OK push $x->[3], 'ouch'; # Error: array reference expected.` [download] لսႽ† ᥲᥒ⚪⟊Ⴙᘓᖇ Ꮅᘓᖇ⎱ Ⴙᥲ𝇋ƙᘓᖇ	[reply] [d/l]
Re^3: Autovivification identification by Random_Walk (Prior) on Aug 02, 2013 at 08:14 UTC
I did not know that. I kinda like it, but I am not sure if it leads to more readable code for those who come after me. Cheers, R. Pereant, qui ante nos nostra dixerunt!	[reply]
Re^2: Autovivification identification by gaurav (Sexton) on Aug 01, 2013 at 10:18 UTC
thanks...I was thinking the same..but was little bit confused..because of amateurishness in Perl	[reply]
Re^3: Autovivification identification by ww (Archbishop) on Aug 01, 2013 at 10:41 UTC
"...amateurishness in Perl" or "amateurishness in the observer?" A little knowledge is a dangerous thing; so is failure to indent for readability.	[reply]
Re^4: Autovivification identification by gaurav (Sexton) on Aug 01, 2013 at 12:37 UTC
I am very thank full to you,but want to make one thing clear ,that don't have any disrespect for Perl.My intention was same as yours',means I was calling my self, an amateur	[reply]