Re: converting libraries into modules

[dragonchild]

In Perl5, libraries and classes are implemented using the same mechanism (packages, usually in their own .pm files), but they're completely different. If you're converting P4-style libraries to P5-style, all you need to do is follow this template.

Old:

[mylibrary1.pl]

sub half {
   my $number = shift;
   return $number / 2;
}

New:

[mylibrary1.pm]

package mylibrary1;

use base 'Exporter';
use vars qw( @EXPORT @EXPORT_OK );

@EXPORT = qw( half ); # These are the ones that are imported if nothin
+g is specified.
@EXPORT_OK = qw( half ); # These are the ones you may specify, if you 
+want.

sub half {
   my $number = shift;
   return $number / 2;
}

1; # All .pm files must end with a true value
__END__

Now, when you use them, you'll do it like this:

Old way:

[myscript.pl]

require 'mylibrary1.pl';

print half( 10 ), "\n";

New way:

[myscript.pl]

use mylibrary1 qw( half );

print half( 10 ), "\n";

Now, the different between @EXPORT and @EXPORT_OK is how you construct the 'use' line. Here's a few examples:

use Foo; # Imports everything in @EXPORT, nothing in @EXPORT_OK

use Foo 'bar'; # Imports 'bar' if it's in @EXPORT_OK. Imports nothing 
+from @EXPORT

use Foo (); # Imports NOTHING from either.

[Courage]

although using Exporter is suggested by, say, h2xs, I think using Exporter isn't a good habbit.
Its not good to pollute namespace.

Using package::utilname(...); $utlobject->utl_method(...); is flexible enough and no real need to save few keystrokes by not pointing package name, and risking to have naming conflict later....

Also, extra dependency on Exporter, and many extra lines in your template to introduce Exporter, do not worth the effort.

[dragonchild]

While I agree with you from a purity perspective, Exporter exists specifically to make the transition between P4 repositories and P5 libraries easier. In other words, Exporter is the exact right tool in this situation.

Now, if the OP wants, we can educate him on better software practices later. But, for now, this solves the OP's problem to a 't'.

[Courage]

I agree, although I do not know what ...solves the OP's problem to a 't'. means :):)