http://www.perlmonks.org?node_id=1077910

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

Let's assume I have a matrix (any sort of n-dimensional array) @m. Better yet, let's pretend it's in an object, so to access it we have to do $o->{m}. Now let's assume I have a dictionary (hash) that assigns names to certain elements in that matrix, which are represented by an anonymous array of coordinates:

%h = ( a => [3, 9, 4], b => [2, 1, 3], c => [9, 7, 2], ... )
Is there any way to represent the element in the matrix using coordinates from the hash (let's also pretend that we're using a variable as the hash key) that is more elegant than $o->{m}[$h{$key}->[0]][$h{$key}->[1]][$h{$key}->[2]]? All those brackets are giving me a headache.

The only alternative I could think of was:

my ($x,$y,$z) = @{$h{$key}}; $o->{m}[$x][$y][$z] = ...
but making three new scalars to clarify a single operation (let's assume that there will only be a single lookup within this scope) seems a little excessive, and if you count the newline it uses the same exact amount of keystrokes. If this is something that I need to do in more than one place, then it would make sense to make something like:
sub matrixGet { my ($o, $x, $y, $z) = @_; return $o->{m}[$x][$y][$z]; } sub matrixSet { my ($o, $x, $y, $z, $val) = @_; $o->{m}[$x][$y][$z] = $val; } ... $o->matrixGet(@{$h{$key}}); $o->matrixSet(@{$h{$key}},5);
or to be more flexible:
sub matrixGet { my ($m, $x, $y, $z) = @_; return $m->[$x][$y][$z]; } ... matrixGet($o->{m},@{$h{$key}});
but now this looks so cumbersome. And what if I have matrices of different dimensions? Now I need matrixGet2D and matrixGet3D and matrixGet4D, etc. And all I really wanted to do was access a certain element using a set of coordinates stored somewhere else for a (relatively) tiny little script I'm writing to manage some data to assist me in a minigame within a game I'm playing. It's already growing to double or triple the size I thought it would originally. But I digress. Is there a simple inline method for using an arrayref as the indexes of a matrix?

And if there's any other blatantly unnecessary step in my code please let me know. It's been a while since I used Perl and mucking about in references was never my strong suit.

Thank you.


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