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Re^3: Return a Deep Hash Reference from Array of Keys

by Laurent_R (Parson)
on Aug 16, 2013 at 21:13 UTC ( #1049797=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Return a Deep Hash Reference from Array of Keys
in thread Return a Deep Hash Reference from Array of Keys

The example under the debugger that I gave works only for a two-level hash dereferencing. It has to be adapted for other levels.

I slightly modified the program you made based on my idea so that it takes into account the number of elements in the array of keys, as follows:

#! /bin/perl use Data::Dumper; my $hash = { 'wheels' => { 'four' => { 'car' => { 'plain' => { 'sporty' => 'honda', 'retro' => 'volkswagon', }, 'fancy' => { 'red' => 'ferrari', 'silver' => 'maserati', }, }, 'truck' => { 'light' => { 'chevy' => 'pickup', }, 'utility' => { 'us' => 'mail', 'city' => 'trash', 'muni' => 'power', 'corp' => { 'dom' => 'dominion p +ower', 'vap' => 'virginia p +ower', }, }, }, }, 'one' => 'Unicycle', 'two' => { 'pedals' => 'bicycle', 'motorized' => 'motorcycle', }, 'three' => 'tricycle', } }; ##--------------------------- ## DEEP REFERENCE ##--------------------------- fetch2($hash, 'wheels'); fetch2($hash, 'wheels', 'four', 'truck'); fetch2($hash, 'wheels', 'four', 'truck', 'utility'); fetch2($hash, 'wheels', 'four', 'truck', 'utility', 'blah'); fetch2($hash, 'wheels', 'four', 'truck', 'utility', 'corp', 'dom'); ## Using your suggested technique sub fetch2 { my ($hash, @keys) = @_; print "==> Fetching [" . join(', ', @keys) . ']' . "\n"; my $command_string = 'print Dumper $hash->' . '{shift @keys}' +x scalar @keys; eval "$command_string"; }
And I get the following output, which seems correct to me:
$ perl deep.pl ==> Fetching [wheels] $VAR1 = { 'three' => 'tricycle', 'one' => 'Unicycle', 'two' => { 'pedals' => 'bicycle', 'motorized' => 'motorcycle' }, 'four' => { 'car' => { 'plain' => { 'sporty' => 'honda', 'retro' => 'volkswagon' }, 'fancy' => { 'silver' => 'maserati', 'red' => 'ferrari' } }, 'truck' => { 'light' => { 'chevy' => 'pickup' }, 'utility' => { 'city' => 'trash', 'muni' => 'power', 'us' => 'mail', 'corp' => { 'dom' => + 'dominion power', 'vap' => + 'virginia power' } } } } }; ==> Fetching [wheels, four, truck] $VAR1 = { 'light' => { 'chevy' => 'pickup' }, 'utility' => { 'city' => 'trash', 'muni' => 'power', 'us' => 'mail', 'corp' => { 'dom' => 'dominion power', 'vap' => 'virginia power' } } }; ==> Fetching [wheels, four, truck, utility] $VAR1 = { 'city' => 'trash', 'muni' => 'power', 'us' => 'mail', 'corp' => { 'dom' => 'dominion power', 'vap' => 'virginia power' } }; ==> Fetching [wheels, four, truck, utility, blah] $VAR1 = undef; ==> Fetching [wheels, four, truck, utility, corp, dom] $VAR1 = 'dominion power';


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Re^4: Return a Deep Hash Reference from Array of Keys
by bratwiz (Sexton) on Sep 13, 2013 at 18:20 UTC
    Yes, that does look right to me also.
      Then you are entitled to upvote my post. ;-)

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