Re: how to replace @ inside of { }

Rob Dixon wrote:
Richard Lee wrote:
Gunnar Hjalmarsson wrote:

C:\home>type test.pl
use Data::Dumper;
my %HoA = (
something => [ qw/val1 val2 val3 and so forth/ ],
something2 => [ qw/vala valb valc and so forth/ ],
something3 => [ qw/valZ valZ1 valZ2 so forth/ ],
);
my %HoH;
while ( <DATA> ) {
/^(\S+)/;
@{ $HoH{$1} }{ @{ $HoA{$1} } } = split;
}
print Dumper \%HoH;

__DATA__
something3 one two three etc
something2 two three and so on
something one two three four five

C:\home>perl test.pl
$VAR1 = {
'something3' => {
'so' => 'three',
'valZ2' => 'two',
'forth' => 'etc',
'valZ1' => 'one',
'valZ' => 'something3'
},
'something2' => {
'so' => 'so',
'valb' => 'two',
'forth' => 'on',
'valc' => 'three',
'vala' => 'something2',
'and' => 'and'
},
'something' => {
'so' => 'four',
'forth' => 'five',
'val2' => 'one',
'val1' => 'something',
'val3' => 'two',
'and' => 'three'
}
};

C:\home>

Hey, this works perfectly, thanks.

I just need to understand more on this

@{ $HoH{$1} }{ @{ $HoA{$1} } } = split;

This is really spinning my heads in all direction trying to see if I can truly understand them instead of just using it.

Yes, it's not the most transparent line of code is it. The while loop is
equivalent to:

while ( <DATA> ) {
my @values = split;
my $key = $values[0];
my $labels = $HoA{$key};
my %map;
@map{@$labels} = @values;
$HoH{$key} = \%map;
}

And IMO it's better written like that.

While I agree that a few temporary variables may increase the readability, I believe that the OP's difficulties to grasp the code has little to do with the coding style. Easier to read code does not replace the need in this case to understand hash slices and references.

--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
.

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