Html - dynamic array

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

Here's something that was lingering in my mind for sometime. I use dynamically named
arrays a lot. I find using them much better when i'm not sure about the quantity of data i have
For example:

$te = HTML::TableExtract->new(keep_headers=> ["Customers","Samples","V
+iolations","Availability"]);
$te->parse($final_content);
$arr_name = "ARR";
my $pages=0;
foreach $ts ($te->tables) 
{
    print "Table Number(" , join(',',$ts->coords), "):\n";
    $rws=0;
    foreach $row ($ts->rows)
    {
        $temp = join (",",@$row);
        my @row_ele = split(/,/,$temp);
        print "$pages,$rws\n";
        ${$arr_name{$pages}}[$rws]=\@row_ele;
#        print ${$arr_name{$pages}}[$rws]->[1]."\n";
        $rws++;
    }
    $pages++;
}
[download]

Here the $final_content is html data with some tables.
Though this code works absolutely fine and with no errors, i still wonder if I should
use something else other than dynamically named arrays.
I use them in almost anything that deals with threads/html or with data for
which i'm not sure about the quantity...Just curious!

Raghu

Comment on Html - dynamic array Download Code

Replies are listed 'Best First'.
Re: Html - dynamic array by GrandFather (Saint) on Jul 24, 2009 at 08:05 UTC
I don't know what you think that does, but it doesn't do it! I strongly recommend that you always use strictures (use strict; use warnings;). Under strictures the line containing `${$arr_name{$pages}}[$rws]=\@row_ele;` generates the error: `Global symbol "%arr_name" requires explicit package name at ...` [download] What you are achieving is autovivifying an entry in the package hash %arr_name. Over time your script will accumulate a hash entry for each page. If something of that sort is your intent then it would be better written using an explicit array of array (AOA): `use strict; use warnings; use HTML::TableExtract; my $te = HTML::TableExtract->new ( keep_headers => ["Customers", "Samples", "Violations", "Availabili +ty"] ); $te->parse ($final_content); my @pages; foreach my $ts ($te->tables ()) { print "Table Number(", join (',', $ts->coords), "):\n"; $rws = 0; push @pages, []; foreach $row ($ts->rows) { my @row_ele = split /,/, join ",", @$row; push @{$pages[-1]}, \@row_ele; print scalar @pages, ',', scalar @{$pages[-1]}, "\n"; } }` [download] True laziness is hard work	[reply] [d/l] [select]
Re: Html - dynamic array by ikegami (Patriarch) on Jul 24, 2009 at 08:10 UTC
Another note, `my $rws = 0; for (...) { $foo[$rws] = ...; $rws++; }` [download] is a weird/convoluted way of doing `for (...) { push @foo, ...; }` [download] You have two instances of unnecessarily using a counter.	[reply] [d/l] [select]
Re: Html - dynamic array by davorg (Chancellor) on Jul 24, 2009 at 07:56 UTC
See "Why it's stupid to 'use a variable as a variable name'" - Part 1, Part 2, Part 3. There are good reasons why `use strict` makes symbolic references (aka "using variables as variable names") illegal. It's a really bad idea. In your case, I can't see any advantage that you have over just using an array called @ARR (though a better naming strategy might be nice). In the general case, you're almost always better off using hashes to store references to arrays. -- See the Copyright notice on my home node. Perl training courses	[reply]
Re: Html - dynamic array by Anonymous Monk on Jul 24, 2009 at 07:52 UTC
Obligatory Why it's stupid to `use a variable as a variable name` - part 1 Why it's stupid to `use a variable as a variable name` - part 2 Why it's stupid to `use a variable as a variable name` - part 3 BTW, you're not even doing it right. You take all the risks of using a variable as a variable name, without any of the tiny syntax benefits.	[reply]


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