perlmeditation
holli
Brothers in perl,<br>
here is a little module that i like to discuss. It is a workaround to the issue that INIT-Blocks are not executed in an <code>eval</code>ed environment like mod_perl and WSH (Windows Scripting Host). Everything else you need to know is in the pod.<br>
Do you thinks itīs well written? do you detect any caveats? what about the name?<br><br>
eager to hear the monks wisdom,<br>
holli
<readmore>
<code>
package Evaled::INIT;
use 5.008;
use strict;
use warnings;
our $VERSION = '0.01';
my $filter;
use Filter::Simple sub
{
return if $filter++;
my $i=0;
while ( $_ =~ s/(^|[\s\t;}])INIT(?!\x00)([\s\n]*|{)/$1INIT\x00 { \&SINIT$i; } \nsub SINIT$i$2/ms ) {$i++;};
s/\x00//msg;
};
1;
__END__
=head1 NAME
Evaled::INIT - Perl extension for executing INIT-sections
=head1 SYNOPSIS
use Evaled::INIT;
=head1 ABSTRACT
When you I<use> a module in an I<eval()>-statement,
then the modules I<INIT>-sections (if any) are not executed. This module can be used to work-around this behaviour.
=head2 VERSION
This is Version 0.1, early beta-state ,-)
=head1 DESCRIPTION
When you I<use> a module in an I<eval()>-statement, like
$mod = "Foo";
eval "use $mod;";
then the modules I<INIT>-sections (if any) are not executed.
Such statements may be used to load unknown modules at runtime,
or might be implicitly caused by an environment like the I<Windows Scripting Host (WSH)> or mod_perl.
Such a WSH-PerlSript is always executed within an I<eval()>.
This behaviour can cause the module to act irregularly.
If you need to use such a module in any I<eval>-statement you can you use this module to work around.
Simply add the line
use Evaled::INIT;
at the top of the modules code (right after the I<package xxx;>-statement).
I<Evaled::INIT> acts as a source-filter.
B<Hint:>
I<A source-filter is a module that can change the sourcecode of the module that uses it to
whatever the filter wants. This happens before the modules code is compiled.>
In this case the filter will replace all
INIT
{
#do something
}
with
INIT
{
&SINITx();
}
sub SINITx
{
#do something
}
where I<x> is the number of the I<BEGIN>-section (there can be more than one) in top-down-order,
starting with 0.
After that conversion you can call the I<SINITx>-Functions as apropriate, like
$mod = "Foo";
eval "use $mod;";
eval "&$mod::SINITx();";
=head2 EXPORT
None by default or query.
=head2 EXAMPLES
=head3 Bad example, INIT is not executed.
#File t.pm
INIT
{
print "INIT\n";
}
1;
#File t.pl
eval "use t.pm;";
print "main\n";
Output:
>>perl t.pl
main
>>
=head3 Good example, INIT can be called.
#File t.pm
use Evaled::INIT;
INIT
{
print "INIT\n";
}
1;
#File t.pl
eval "use t.pm; &t::SINIT0();";
print "main\n";
Output:
>>perl t.pl
INIT
main
>>
=head3 Good example, INIT still works
#of course the module will still work without eval
#File t.pm
use Evaled::INIT;
INIT
{
print "INIT\n";
}
1;
#File t.pl
use t.pm;
print "main\n";
Output:
>>perl t.pl
INIT
main
>>
=head1 AUTHOR
Markus Holzer (m.holzer/at/kvsaarland.de)
=head1 COPYRIGHT AND LICENSE
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
=cut
</code>
</readmore>
<p><small>Retitled by [davido].</small></p>