Re: Reloading Modules
Ted Prah wrote:
Hi again,
I'm having trouble seeing module changes when I reload
a script that uses it.
That's because Reload.pm doesn't re-exports the symbols when reloading
the module and test.pl doesn't call import() because it sees the module
in %INC, therefore it still sees the old sub till the moment it gets
recompiled. Below you will find a complete analysis.
I'm using Apache::Reload and my test
script/module is as follows:
test.pl
#!/usr/local/bin/perl
use strict;
use warnings;
use My::Test qw(:subs);
print Content-type: text/plain\r\n\r\n;
test1();
Test.pm
package My::Test;
use strict;
use warnings;
BEGIN {
use Exporter ();
our (@ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);
@ISA = qw(Exporter);
@EXPORT= qw();
@EXPORT_OK = qw();
%EXPORT_TAGS = (
subs = [qw(test1)],
);
Exporter::export_ok_tags('subs');
}
sub test1 { print In test1 func\n; }
1;
adjust the test.pl to do:
test1(); print \test1, \n;
#test2(); print \test2, \n;
and My::Test.pm to:
...
warn test1:, \test1, \n;
#warn test2:, \test2, \n;
sub test1 { print In test1 func\n; }
#sub test2 { print In test2 func\n; }
...
The first time you run the script you will see:
output:
In test1 func
CODE(0x85ad38c)
error_log:
test1:CODE(0x85ad38c)
you can see that both test1 and My::Test::test1 point to the same sub.
When I modify sub test1, and I reload - no changes appear
in the browser. The following gets printed to error_log:
Subroutine test1 redefined at /export/home/httpd/cgi-bin/My/Test.pm line 22.
output:
In test1 func
CODE(0x85ad38c)
error_log:
test1:CODE(0x84ee110)
as you see the test1 is not the same as My::Test::test1
When I touch test.pl - the changes appear. The following gets printed
to error_log:
Subroutine test1 redefined at /export/home/httpd/cgi-bin/My/test.pl line 5
output:
In test11 func
CODE(0x84ee110)
now it points to the recent My::Test::test1
In that way you can debug any mysteries in Perl code.
Now, how to solve this problem. For example comment out
require $key;
in Reload.pm
that way, test.pl will see that My::Test is not in %INC, and require it
+ call its import() method.
Tell if this worked and we may adjust Reload.pm to have a special mode
where it makes Perl forget about modified modules and let the code that
loaded them in first place do the loading (and therefore the importing).
Finally, if I add a new subroutine test2 to Test.pm, export it, and
update the test.pl script to call test2, the script fails with an
Internal
Server Error. The following gets printed to error_log:
test2 is not exported by the My::Test module at
/export/home/httpd/cgi-bin/My/test.pl line 5
[Wed May 22 15:26:12 2002] [error] Can't continue after import errors at
/export/home/httpd/cgi-bin/My/test.pl line 5
BEGIN failed--compilation aborted at /export/home/httpd/cgi-bin/
My/test.pl line 5.
Then, when I restart the server, the script runs fine.
Hmm, this one is different. Seems like a bug in Exporter.
if you remove Reload.pm from the setup, so it won't confuse you and
adjust the code to do:
do My/Test.pm;
My::Test-import(':subs');
you will see that it fails as well. This code acts like Reload.pm, but
always reloads the module. So it's not Reload.pm's fault.
Is anybody else familiar with this Exporter's (mis)behavior?
The solution that I see is to use something like this:
package My::Test;
use strict;
use warnings;
sub import {
my $package = shift;
no strict 'refs';
for (@_) {
*{ (caller)[0] . ::$_ } = \{$_};
}
}
sub test1 { print In test1 func\n; }
sub test2 { print In test2 func\n; }
1;
If somebody else can see the problem with Exporter may be we need to run
it through p5p.
__
Stas BekmanJAm_pH -- Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide --- http://perl.apache.org
mailto:[EMAIL PROTECTED] http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org http://ticketmaster.com
Re: Reloading Modules
Thanks for the input Stats. I found your debugging methodology
to be very informative and especially useful in a mod_perl environment.
I tried your suggestion of commenting out
require $key;
in Reload.pm, but it did not work for me. I'd be happy to try
any other suggestions you might have.
Your code to work around Exporter worked fine. However,
I think I'll stick with using Exporter so that I can make use
of the export tags.
Thanks again!
Ted
Stas Bekman wrote:
Ted Prah wrote:
Hi again,
I'm having trouble seeing module changes when I reload
a script that uses it.
That's because Reload.pm doesn't re-exports the symbols when reloading
the module and test.pl doesn't call import() because it sees the module
in %INC, therefore it still sees the old sub till the moment it gets
recompiled. Below you will find a complete analysis.
I'm using Apache::Reload and my test
script/module is as follows:
test.pl
#!/usr/local/bin/perl
use strict;
use warnings;
use My::Test qw(:subs);
print Content-type: text/plain\r\n\r\n;
test1();
Test.pm
package My::Test;
use strict;
use warnings;
BEGIN {
use Exporter ();
our (@ISA, @EXPORT, @EXPORT_OK, %EXPORT_TAGS);
@ISA = qw(Exporter);
@EXPORT= qw();
@EXPORT_OK = qw();
%EXPORT_TAGS = (
subs = [qw(test1)],
);
Exporter::export_ok_tags('subs');
}
sub test1 { print In test1 func\n; }
1;
adjust the test.pl to do:
test1(); print \test1, \n;
#test2(); print \test2, \n;
and My::Test.pm to:
...
warn test1:, \test1, \n;
#warn test2:, \test2, \n;
sub test1 { print In test1 func\n; }
#sub test2 { print In test2 func\n; }
...
The first time you run the script you will see:
output:
In test1 func
CODE(0x85ad38c)
error_log:
test1:CODE(0x85ad38c)
you can see that both test1 and My::Test::test1 point to the same sub.
When I modify sub test1, and I reload - no changes appear
in the browser. The following gets printed to error_log:
Subroutine test1 redefined at /export/home/httpd/cgi-bin/My/Test.pm line 22.
output:
In test1 func
CODE(0x85ad38c)
error_log:
test1:CODE(0x84ee110)
as you see the test1 is not the same as My::Test::test1
When I touch test.pl - the changes appear. The following gets printed
to error_log:
Subroutine test1 redefined at /export/home/httpd/cgi-bin/My/test.pl line 5
output:
In test11 func
CODE(0x84ee110)
now it points to the recent My::Test::test1
In that way you can debug any mysteries in Perl code.
Now, how to solve this problem. For example comment out
require $key;
in Reload.pm
that way, test.pl will see that My::Test is not in %INC, and require it
+ call its import() method.
Tell if this worked and we may adjust Reload.pm to have a special mode
where it makes Perl forget about modified modules and let the code that
loaded them in first place do the loading (and therefore the importing).
Finally, if I add a new subroutine test2 to Test.pm, export it, and
update the test.pl script to call test2, the script fails with an
Internal
Server Error. The following gets printed to error_log:
test2 is not exported by the My::Test module at
/export/home/httpd/cgi-bin/My/test.pl line 5
[Wed May 22 15:26:12 2002] [error] Can't continue after import errors at
/export/home/httpd/cgi-bin/My/test.pl line 5
BEGIN failed--compilation aborted at /export/home/httpd/cgi-bin/
My/test.pl line 5.
Then, when I restart the server, the script runs fine.
Hmm, this one is different. Seems like a bug in Exporter.
if you remove Reload.pm from the setup, so it won't confuse you and
adjust the code to do:
do My/Test.pm;
My::Test-import(':subs');
you will see that it fails as well. This code acts like Reload.pm, but
always reloads the module. So it's not Reload.pm's fault.
Is anybody else familiar with this Exporter's (mis)behavior?
The solution that I see is to use something like this:
package My::Test;
use strict;
use warnings;
sub import {
my $package = shift;
no strict 'refs';
for (@_) {
*{ (caller)[0] . ::$_ } = \{$_};
}
}
sub test1 { print In test1 func\n; }
sub test2 { print In test2 func\n; }
1;
If somebody else can see the problem with Exporter may be we need to run
it through p5p.
__
Stas BekmanJAm_pH -- Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide --- http://perl.apache.org
mailto:[EMAIL PROTECTED] http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org http://ticketmaster.com
Re: Reloading Modules
Ted Prah wrote:
Thanks for the input Stats. I found your debugging methodology
to be very informative and especially useful in a mod_perl environment.
I tried your suggestion of commenting out
require $key;
in Reload.pm, but it did not work for me. I'd be happy to try
any other suggestions you might have.
But did you debug whether the module was reloaded from test.pl with the
modified Reload.pm? If so was the import() called? If not, try to have
it as a separate call:
require My::Test;
My::Test-import(':subs');
Your code to work around Exporter worked fine. However,
I think I'll stick with using Exporter so that I can make use
of the export tags.
But it doesn't seem to work? You can easily extend the import() function
I've suggested to suppport tags.
__
Stas BekmanJAm_pH -- Just Another mod_perl Hacker
http://stason.org/ mod_perl Guide --- http://perl.apache.org
mailto:[EMAIL PROTECTED] http://use.perl.org http://apacheweek.com
http://modperlbook.org http://apache.org http://ticketmaster.com
