[26400] in Perl-Users-Digest
Perl-Users Digest, Issue: 8571 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Oct 26 06:05:29 2005
Date: Wed, 26 Oct 2005 03:05:05 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Wed, 26 Oct 2005 Volume: 10 Number: 8571
Today's topics:
FAQ 4.44 How do I test whether two arrays or hashes are <comdog@pair.com>
Re: Moving data structure around better than globals? <noreply@gunnar.cc>
Re: Moving data structure around better than globals? <noreply@gunnar.cc>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 26 Oct 2005 10:03:01 +0000 (UTC)
From: PerlFAQ Server <comdog@pair.com>
Subject: FAQ 4.44 How do I test whether two arrays or hashes are equal?
Message-Id: <djnk8k$7a3$1@reader2.panix.com>
This message is one of several periodic postings to comp.lang.perl.misc
intended to make it easier for perl programmers to find answers to
common questions. The core of this message represents an excerpt
from the documentation provided with Perl.
--------------------------------------------------------------------
4.44: How do I test whether two arrays or hashes are equal?
The following code works for single-level arrays. It uses a stringwise
comparison, and does not distinguish defined versus undefined empty
strings. Modify if you have other needs.
$are_equal = compare_arrays(\@frogs, \@toads);
sub compare_arrays {
my ($first, $second) = @_;
no warnings; # silence spurious -w undef complaints
return 0 unless @$first == @$second;
for (my $i = 0; $i < @$first; $i++) {
return 0 if $first->[$i] ne $second->[$i];
}
return 1;
}
For multilevel structures, you may wish to use an approach more like
this one. It uses the CPAN module FreezeThaw:
use FreezeThaw qw(cmpStr);
@a = @b = ( "this", "that", [ "more", "stuff" ] );
printf "a and b contain %s arrays\n",
cmpStr(\@a, \@b) == 0
? "the same"
: "different";
This approach also works for comparing hashes. Here we'll demonstrate
two different answers:
use FreezeThaw qw(cmpStr cmpStrHard);
%a = %b = ( "this" => "that", "extra" => [ "more", "stuff" ] );
$a{EXTRA} = \%b;
$b{EXTRA} = \%a;
printf "a and b contain %s hashes\n",
cmpStr(\%a, \%b) == 0 ? "the same" : "different";
printf "a and b contain %s hashes\n",
cmpStrHard(\%a, \%b) == 0 ? "the same" : "different";
The first reports that both those the hashes contain the same data,
while the second reports that they do not. Which you prefer is left as
an exercise to the reader.
--------------------------------------------------------------------
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------------------------------
Date: Wed, 26 Oct 2005 12:00:47 +0200
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: Moving data structure around better than globals?
Message-Id: <3s92i7Fmsc9dU1@individual.net>
Tad McClellan wrote:
> Gunnar Hjalmarsson wrote:
>>I have accepted that package globals as well as file scoped lexicals
>>should be avoided if possible,
>
> I'd say "if practicable" rather than "if possible".
>
> It is the _abuse_ of global variables that is often warned against,
> they do have their place.
Yeah, I took it to an extreme this time, contrary to my habit. ;-)
>>I'm passing $d around to just about all the functions,
>
> So then, it would hit my "impracticable" limit. :-)
>
>>and it struck me
>>that this approach actually is very similar to using global variables.
>
> I very often have a single global hash with "configuration"
> type values in it.
>
>>So my question is: Why would this be better (if you think it is)?
>
> I wouldn't say that passing the same arg in every function call
> is better.
Thanks for confirming my feeling.
My "impracticable" approach is well working, though, so I won't change
it now. But I'll keep this in mind for next time.
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: Wed, 26 Oct 2005 12:00:52 +0200
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: Moving data structure around better than globals?
Message-Id: <3s92ibFmsc9dU2@individual.net>
Mothra wrote:
> Gunnar Hjalmarsson wrote:
>>I have accepted that package globals as well as file scoped lexicals
>>should be avoided if possible, and hence a program I'm currently
>>writing does not include any globals.
>
> (snipped)
>
> I asked something similar in the past.
>
> http://tinyurl.com/8bbel
Thanks for the link. That discussion is absolutly relevant to the topic
I raised.
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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End of Perl-Users Digest V10 Issue 8571
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