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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