On Feb 13, Barry Kingsbury said:
>I have created the following data structure:
>
>%mailings = ( tv => { mail_demo_key => "Demo License Key for TotalView",
> mail_thank_you => "Thank you for downloading
>TotalView",
> pdf => LOCATION_OF_PDF,
> location => LOCATION_OF_DEMO_REPLY,
> text => LOCATION_OF_INSTRUCT,
> text_brochure => LOCATION_OF_BROCHURE },
> cr => { mail_demo_key => "Demo License Key for JNI Bridge
>and TotalView",
> mail_thank_you => "Thank you for downloading the
>CodeRoad JNI Bridge",
> pdf => LOCATION_OF_CR_PDF,
> location => LOCATION_OF_CR_DEMO_REPLY,
> text => LOCATION_OF_CR_INSTRUCT,
> text_brochure => LOCATION_OF_CR_BROCHURE }
> );
It's scary to build a data structure you don't know how to access.
%hash = (
key1 => {
subkey1 => 'value 1',
subkey2 => 'value 2',
},
key2 => {
subkey1 => 'value A',
subkey2 => 'value B',
},
);
That's the same basic idea as your hash above.
> print "$key => " . %{$mailings{$form_name}}->{$key} . "\n";
That's a crufty, not-supposed-to-work syntax.
> print "$key => " . ${$mailings{$form_name}}{$key} . "\n";
That's more work than necessary.
>I have no idea what this syntax is saying or doing and why the two
>different forms of the hash reference are working.
>
>Can some guru explain?
<guru>
The first one works "accidentally". %H->{key} works the same way
$hash{key} does, but it's an anomoly, since the LHS (left-hand side) of ->
is SUPPOSED to be a reference. Replacing 'H' with $hash{key1} gives us
the syntax you had, %{ $hash{key1} }->{subkey1}.
The second works logically. Start with $H{key}, and replace 'H' with
$hash{key1} and you get ${ $hash{key1} }{subkey1}.
But here's the kicker. When you have a value from a hash or an array, and
it's a reference, and you want to get at some value further embedded in
it, you don't need all those {}'s and ->'s to get the job done.
$hash{key1}{subkey1} works the same as ${ $hash{key1} }{subkey1}, but
looks a whole lot nicer.
</guru>
For more fun-time reference reading, check out
perldoc perlreftut
perldoc perlref
perldoc perldsc
perldoc perllol
(The last one is NOT about humor etiquette in the Perl community.)
--
Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/
<stu> what does y/// stand for? <tenderpuss> why, yansliterate of course.
[ I'm looking for programming work. If you like my work, let me know. ]
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