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

I wish there was ... dream dream .. hash, key, value functions ... key value pair references... dream dream...

my $hash = { key => "value" } ;
foreach( keys %{ $myHash } } {
   doSomething( \key $myHash->{$_} ) ; # or maybe without \
}
sub doSomething {
    print "key = " . key $_[0] . "\n" ;
    print( ( value $_[0] ) . "\n" ) ;
    print( ( hash $_[0] )->{key $_[0]} . "\n" ) ;
}
__END__
key = key
value
value

[download]

or:

my $hash = { key1 => key $hash->{key1} } ;
print key $hash->{ key1 } ;
__END__
key1

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or:

my $hash = { key1 => "" } ;
print key $hash->{ key1 } ;
__END__
Not a key value pair reference at line 2

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or:

my $hash = { key1 => { key2 => \key $hash->{key1} } } ;
print key $hash->{ key1 }->{ key2 } ;
__END__
key1

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or another one:

my $key = "key1" ;
my $hash = { \$key => ...} ;
print $key . "\n" ;
print ( key $key ) . "\n" ;
__END__
KEY0x83412523
key1

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dream starts to repeat itself:

my $key = "key1" ;
my $hash = { \$key => "value" } ;
print( ( hash $key )->{ key1 } . "\n" ) ;
print( value $key ) ;
__END__
value
value

[download]

And then I woke up...

Weird dream, I should go to a monk dream teller...

PS Please don't look at this code syntactically or start to look for typos. This is just free drawn and of course doesn't compile. I just like to see if anyone else ever felt something like this could be useful.

Replies are listed 'Best First'.
Re: key value pair reference?
by Corion (Patriarch) on May 14, 2018 at 11:48 UTC

    Do you want to get a magical variable that keeps together a value, its hash key and the hash where they originated from?

    package HashTriplet;
use strict;

sub new {
    my( $class, %options ) = @_;
    bless \%options => $class
}

sub hash { $_[0]->{hash} }
sub key  { $_[0]->{key} }

sub value {
    my( $self ) = @_;
    $self->hash->{ $self->key }
}

1;

package main;
use strict;

my $myHash = { key => "value" } ;
foreach( keys %{ $myHash } ) {
   doSomething( HashTriplet->new( hash => $myHash, key => $_ ));
}

sub doSomething {
warn $_[0];
warn $_[0]->key;
    print "key = " . $_[0]->key . "\n";
    print( (  $_[0]->value ) . "\n" ) ;
    print( (  $_[0]->hash )->{ $_[0]->key } . "\n" ) ;
}
__END__

    [download]

    If you want the additional syntax trickery to make Perl treat key $x; as $x->key you will need to fiddle around a bit with prototypes, but as I'm a bit unclear on the purpose of your data structure, I'll just stop here.

[reply]
[d/l]
[select]
Re: key value pair reference?
by BillKSmith (Monsignor) on May 14, 2018 at 14:16 UTC
[reply]
      Hehe, not even close
[reply]

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