Re^2: Anonymous Reference???

"An array can ONLY contain scalar elements."

Strictly speaking, you were not 100% correct as the following code is valid:

use Data::Dumper;

use strict;
use warnings;

my @a = ((1,2,3), (4,5,6));
print $a[3];
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So array can contain array. However Perl "flattens" the inner arrays, and does not remember the boundary information. This made it impossible to use this way to represent multi-dimentional array, and the array of array ref comes to rescue.

Update: Yes, the example sk given in his reply demos my point better.

However I disagree with his conclusion. I don't think either side is really wrong, and it really depends on whether you look at it from a syntax point of view (my view) or an internal represent view.

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Re^3: Anonymous Reference??? by chromatic (Archbishop) on Sep 12, 2005 at 04:24 UTC
This is incorrect. In this code: `my @a = ((1,2,3), (4,5,6));` ... there is only one array: `@a`. Everything else is a list. Lists are not arrays; lists and arrays behave very differently in various contexts, for example. The parentheses in the expression are for grouping to change the precedence of the right-side of the assignment, not to create lists (and especially not to create arrays).	[reply] [d/l] [select]
Re^4: Anonymous Reference??? by sk (Curate) on Sep 12, 2005 at 04:38 UTC
From this thread Scalars, Lists, and Arrays guess that is called a list expression and not a list itself. :) I think pg's example could have been something like this - `my @a = (1,2,3); my @b = (@a,4,5,6);` here we use an array a in creating another array b. I think this just demonstrates that one can use arrays to create other arrays (you don't always need scalars separated by commas)...However I would not use the phrase arrays can contain arrays because once the array a is flattened under the list context the final array b just contains scalars In short I agree with halley.	[reply] [d/l]
Re^3: Anonymous Reference??? by halley (Prior) on Sep 12, 2005 at 12:31 UTC
pg writes: I don't think either side is really wrong, and it really depends on whether you look at it from a syntax point of view (my view) or an internal represent view. Syntax is only useful insofar as it develops a data structure. Data structures are what enable algorithms. Following all of perl's "there is more than one way to phrase it" syntax eccentricities will just confuse you; conversely, recognizing perl's very few, very simple, very self-consistent data structures will let you accomplish many algorithms with few errors borne of such confusion. a scalar is O(1) in storage; `undef`, int, real, string, or reference; sometimes there are cached alternative representations but it's still O(1) an array contains a known number, zero or more, of scalars a hash associates zero or more pairs; each pair is a unique string key and an arbitrary scalar value (globs are public implementation details of the machine, skipped for this discussion) Lists have no name and no known length. You can't take `$#list` or `$list[-1]` or even `$list[3]` without a conversion to array first. Lists are not a first-class storage data structure, but are the product of processing the syntax of literals, or the product of iteration. -- `[ e d @ h a l l e y . c c ]`	[reply] [d/l] [select]