I think the only difference between the two is Stat's code do the things of
sharing vars across modules really.
Under mod_perl,the situation is very different from common CGI environment,and
the vars sharing sometimes is useful and needed.
I hope I'm correct.If not,the criticism are welcome.
-----Original Message-----
>From: John Doe <[EMAIL PROTECTED]>
>Sent: Jan 16, 2006 4:09 AM
>To: beginners@perl.org
>Subject: Re: about the var's scope
>
>Shawn Corey am Montag, 16. Januar 2006 04.12:
>[...]
>> > Ok, it would be interesting to look deeper into the mess of different
>> > variables all named with the same name $q, exported across the modules,
>> > overwritten by several imports...
>> >
>> > What do you want to achieve with your code? It looks really strange (hm,
>> > at least to me).
>> >
>> > joe
>>
>> All the variables $q in the packages have been shunted aside into the
>> deep, dark bit bucket of oblivion.
>>
>> As I said before:
>>
>> $main::q = \*My::HTML::q;
>> $main::q = \*My::Doc::q;
>>
>> $My::HTML::q and $My::Doc::q no longer exist; they are aliases to
>> $main::q. In the modules, $q no longer exists; it is an alias for
>> $main::q. Whenever you say $q in the modules, you really mean $main::q.
>> The modules do not import anything; they export any changes to $main::q;
>> via the phrase '$q'.
>
>Hi again Shawn,
>
>I have a question concerning the code presented in the OP. I repeat it for
>better overview:
>
>==== Version 1 ====
> script.pl:
> ----------------
> use vars qw($q);
> use CGI;
> use lib qw(.);
> use My::HTML qw($q); # My/HTML.pm is in the same dir as script.pl
> use My::Doc qw($q); # Ditto
> $q = new CGI;
>
> My::HTML::printmyheader();
>
> My/HTML.pm
> ----------------
> package My::HTML;
> use strict;
>
> BEGIN {
> use Exporter ();
> @My::HTML::ISA = qw(Exporter);
> @My::HTML::EXPORT = qw();
> @My::HTML::EXPORT_OK = qw($q);
> }
> use vars qw($q);
> use My::Doc qw($q);
> sub printmyheader{
> # Whatever you want to do with $q... e.g.
> print $q->header();
> My::Doc::printtitle('Guide');
> }
> 1;
>
> My/Doc.pm
> ----------------
> package My::Doc;
> use strict;
>
> BEGIN {
> use Exporter ();
> @My::Doc::ISA = qw(Exporter);
> @My::Doc::EXPORT = qw();
> @My::Doc::EXPORT_OK = qw($q);
> }
> use vars qw($q);
> sub printtitle{
> my $title = shift || 'None';
> print $q->h1($title);
> }
> 1;
>==== END Version 1====
>
>The code demonstrates the usage of the use vars pragma and the Exporter.
>
>However, my personal feeling ist that in a bigger project it is eventually bad
>style to use globals this way?!?
>
>Do you agree? Or do I - again - overlook something?
>
>See the equivalent code below as an alternative:
>
>==== Version 2 ====
> script.pl:
> ----------------
> use CGI;
> use lib qw(.);
> use My::HTML;
> my $q = new CGI;
>
> My::HTML::printmyheader($q);
>
> My/HTML.pm
> ----------------
> package My::HTML;
> use strict;
>
> use My::Doc;
> sub printmyheader{
> my $q=shift;
> ### DO CHECKS HERE
> # Whatever you want to do with $q... e.g.
> print $q->header();
> My::Doc::printtitle($q, 'Guide');
> }
> 1;
>
> My/Doc.pm
> ----------------
> package My::Doc;
> use strict;
>
> sub printtitle{
> my $q=shift;
> ### DO CHECKS HERE
> my $title = shift || 'None';
> print $q->h1($title);
> }
> 1;
>==== END Version 2====
>
>This version does the same, is shorter, is easier to understand for some
>people, does not require Exporter, and does not need use'ing My::Doc in the
>main script (it's more modular).
>
>Does this 2nd version lack any features/magic present in the 1st?
>(Apart from demonstrating use vars / Exporter of course)
>
>Any comments are very appreciated!
>
>greetings
>joe
>
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