Directly Dereferencing an Array Reference to an Array

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

Fellow Monks and Monkettes:

  my @temp = (2,3,4);
  $selects[0] = [@temp];
[download]

After the above setup,

  $refdates = $selects[0];
  @workdts = @$refdates;
[download]

works, but...

  @workdts = @$selects[0];
[download]

...does not.

Why? I could use an enlightened bonk on the head. :)

Don Wilde
"There's more than one level to any answer."

Comment on Directly Dereferencing an Array Reference to an Array Select or Download Code

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Re: Directly Dereferencing an Array Reference to an Array by cdarke (Prior) on Aug 30, 2006 at 17:49 UTC
In a word: precedence. Perl is actually looking for a scalar called $selects, you need a touch of the old curlies: @workdts = @{$selects[0]} to force precedence your way.	[reply]
Re: Directly Dereferencing an Array Reference to an Array by Velaki (Chaplain) on Aug 30, 2006 at 17:52 UTC
Turning on strict and warnings helps a boodle. Converting your code to `#!/usr/bin/perl use strict; use warnings; my @temp = (2,3,4); my @selects; $selects[0] = [@temp]; my $refdates = $selects[0]; #my @workdts = @$refdates; my @workdts = @$selects[0]; print "$_\n" for @workdts;` [download] gives me `Global symbol "$selects" requires explicit package name at ./p line...` [download] Now since we explicitly declared `@selects` as an array, then `$selects[0]` should be an array element, which it is, and we only need to cast that reference to an array type. Well, since `@` binds tighter than subscripting, the compiler thought we were trying to use `@$selects`, which implies that `$selects`, the scalar, exists. Since it doesn't, we need to enforce what we want with braces. `@{$selects[0]}` [download] This will give us the result we desire. Hope this helped, -v. "Perl. There is no substitute."	[reply] [d/l] [select]
Re^2: Directly Dereferencing an Array Reference to an Array by samizdat (Vicar) on Aug 30, 2006 at 17:59 UTC
Many thanks! Before I get heaped with an OD of ashes, the reason I don't have strict and warnings on is that this is embperl code embedded in a web page. Embperl does things (such as loading once with [! !]) which do not fare well under strict pragmas. Don Wilde "There's more than one level to any answer."	[reply]