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The Basics
Id: 81711
Status: open
Priority: 0/
Queue: Class-Factory

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Owner: Nobody in particular
Requestors: sabol [...] alderaan.gsfc.nasa.gov
Cc:
AdminCc:

Bug Information
Severity: Wishlist
Broken in:
  • 0.01
  • 0.02
  • 0.03
  • 1.00
  • 1.02
  • 1.03
  • 1.04
  • 1.05
  • 1.06
Fixed in: (no value)



Subject: Avoid eval "require $object_class"; use eval { require $object_class_file } instead
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It would be nice if Class::Factory would avoid using eval "require $object_class"; to load modules. I'm sure I don't have to tell you that eval EXPR is much less efficient compared to eval BLOCK. It's especially good to avoid it in a mod_perl environment, I think, where the code might be executed many times. I recommend the following code instead: (my $object_class_file = $object_class) =~ s-::|'-/-g; $object_class_file .= ".pm" if ($object_class_file !~ /\.p[lmh]$/); eval { require $object_class_file }; See http://www.perlmonks.org/?node_id=634438 for related discussion. Tip of the hat to PerlMonk tye for posting code similar to the above in that thread. (It correctly deals with modules with names like Acme::Don't and D'oh.) The Class::Factory code indicates that the original author intended to support $object_class values that end in ".p[lmh]", i.e. file names, I presume. I'm not sure how useful that is in practice, but I've attempted to retain that support with the "if ($object_class_file !~ /\.p[lmh]$/)" conditional shown above. If you want to be conservative, you could use the "eval BLOCK" form only if ($object_class =~ /^\w+(?:::\w+)*$/) and use "eval EXPR" in all other cases. I suspect that would cover 98% of Class::Factory's usage. What do you think?
Subject: Re: [rt.cpan.org #81711] Avoid eval "require $object_class"; use eval { require $object_class_file } instead
Date: Wed, 5 Dec 2012 13:34:51 -0800
To: bug-Class-Factory [...] rt.cpan.org
From: Fred Moyer <fred [...] redhotpenguin.com>
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Patches welcome :) On Tue, Dec 4, 2012 at 9:05 PM, sabol@alderaan.gsfc.nasa.gov via RT <bug-Class-Factory@rt.cpan.org> wrote: Show quoted text
> Wed Dec 05 00:05:11 2012: Request 81711 was acted upon. > Transaction: Ticket created by sabol@alderaan.gsfc.nasa.gov > Queue: Class-Factory > Subject: Avoid eval "require $object_class"; use eval { require > $object_class_file } instead > Broken in: 0.01, 0.02, 0.03, 1.00, 1.02, 1.03, 1.04, 1.05, 1.06 > Severity: Wishlist > Owner: Nobody > Requestors: sabol@alderaan.gsfc.nasa.gov > Status: new > Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=81711 > > > > It would be nice if Class::Factory would avoid using > > eval "require $object_class"; > > to load modules. I'm sure I don't have to tell you that eval EXPR is > much less efficient compared to eval BLOCK. It's especially good to > avoid it in a mod_perl environment, I think, where the code might be > executed many times. > > I recommend the following code instead: > > (my $object_class_file = $object_class) =~ s-::|'-/-g; > $object_class_file .= ".pm" if ($object_class_file !~ /\.p[lmh]$/); > eval { require $object_class_file }; > > See http://www.perlmonks.org/?node_id=634438 for related discussion. Tip > of the hat to PerlMonk tye for posting code similar to the above in that > thread. (It correctly deals with modules with names like Acme::Don't and > D'oh.) > > The Class::Factory code indicates that the original author intended to > support $object_class values that end in ".p[lmh]", i.e. file names, I > presume. I'm not sure how useful that is in practice, but I've attempted > to retain that support with the "if ($object_class_file !~ /\.p[lmh]$/)" > conditional shown above. > > If you want to be conservative, you could use the "eval BLOCK" form only > if ($object_class =~ /^\w+(?:::\w+)*$/) and use "eval EXPR" in all other > cases. I suspect that would cover 98% of Class::Factory's usage. > > What do you think?
From: sabol [...] alderaan.gsfc.nasa.gov
On Wed Dec 05 16:35:02 2012, fred@redhotpenguin.com wrote: Show quoted text
> Patches welcome :)
Attached. All tests pass on my Linux platform, but the test suite doesn't exactly cover all the possibilities. Regarding the following code that comes right before the eval: if ( $INC{ $object_class } ) { $item->factory_log( "Looks like class '$object_class' was already ", "included; no further work necessary" ); } else { ... Older versions of Class::Factory do not have this. I suspect it was added to avoid the speed penalty of "eval EXPR". With the code modified to use "eval BLOCK", I think it is unnecessary. Or do you feel the logging is useful? Also, Perl::Critic complains about a number of "return undef" statements in the Class::Factory code. I don't know how you feel about that, but they do seem ill-advised. Some indenting tabs sneaked into the code (lines 190-197, get_registered_class method). If you're a strict anti-tabs person, you might want to untabify those lines.
Subject: ClassFactory.patch
--- Factory.pm 2007-11-06 19:06:54.000000000 -0500 +++ ../../blib/lib/Class/Factory.pm 2012-12-05 19:13:52.371697000 -0500 @@ -4,7 +4,7 @@ use strict; -$Class::Factory::VERSION = '1.06'; +$Class::Factory::VERSION = '1.07'; my %CLASS_BY_FACTORY_AND_TYPE = (); my %FACTORY_INFO_BY_CLASS = (); @@ -81,11 +81,13 @@ "included; no further work necessary" ); } else { - eval "require $object_class"; + (my $object_class_file = $object_class) =~ s-::|\'-/-g; + $object_class_file .= '.pm' unless ($object_class_file =~ /\.p[hlm]$/); + eval { require $object_class_file }; if ( $@ ) { $item->factory_error( "Cannot add factory type '$object_type' to ", - "class '$class': factory class '$object_class' ", - "cannot be required: $@" ); + "class '$class': factory class ", + "'$object_class' cannot be required: $@" ); return undef; } }
Subject: Re: [rt.cpan.org #81711] Avoid eval "require $object_class"; use eval { require $object_class_file } instead
Date: Wed, 5 Dec 2012 22:00:01 -0800
To: bug-Class-Factory [...] rt.cpan.org
From: Fred Moyer <fred [...] redhotpenguin.com>
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Great, I'll merge this patch and do a release. I don't have a preference on the additional items you mentioned. Feel free to make additional changes if you want. I can provide you with a CO-MAINT cpan bit if you feel so inclined, so you can do the releases. On Wed, Dec 5, 2012 at 4:36 PM, sabol@alderaan.gsfc.nasa.gov via RT <bug-Class-Factory@rt.cpan.org> wrote: Show quoted text
> Queue: Class-Factory > Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=81711 > > > On Wed Dec 05 16:35:02 2012, fred@redhotpenguin.com wrote:
>> Patches welcome :)
> > Attached. All tests pass on my Linux platform, but the test suite > doesn't exactly cover all the possibilities. > > Regarding the following code that comes right before the eval: > > if ( $INC{ $object_class } ) { > $item->factory_log( "Looks like class '$object_class' was already ", > "included; no further work necessary" ); > } > else { > ... > > Older versions of Class::Factory do not have this. I suspect it was > added to avoid the speed penalty of "eval EXPR". With the code modified > to use "eval BLOCK", I think it is unnecessary. Or do you feel the > logging is useful? > > Also, Perl::Critic complains about a number of "return undef" statements > in the Class::Factory code. I don't know how you feel about that, but > they do seem ill-advised. > > Some indenting tabs sneaked into the code (lines 190-197, > get_registered_class method). If you're a strict anti-tabs person, you > might want to untabify those lines.


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