UNIVERSAL::require broke my tests

[Ovid]

This was *real fun* to track down.  Here's a minimal test case of what
was happening:

  #!/usr/bin/perl 

  use strict;
  use warnings;

  use HTML::TokeParser qw;

  print "here";

I run that and it prints 'here', even though HTML::TokeParser does not
export 'no_such_function'.  No errors or warnings produced.

Meanwhile, in code many modules away, UNIVERSAL::require is loaded and
my code goes boom!  Here's another minimal test case:

  #!/usr/bin/perl 

  use strict;
  use warnings;

  use UNIVERSAL::require;
  use HTML::TokeParser qw;

  print "here";

That produces:

  :!perl -Ilib parse.pl
  "no_such_function" is not exported by the HTML::TokeParser module
  Can't continue after import errors at parse.pl line 7
  BEGIN failed--compilation aborted at parse.pl line 7.

So it's great that I can now easily track this sort of error down, but
it's not great that the code mysteriously stops working.

Cheers,
Ovid

--

Buy the book -- http://www.oreilly.com/catalog/perlhks/
Perl and CGI -- http://users.easystreet.com/ovid/cgi_course/

Re: UNIVERSAL::require broke my tests

[brian d foy]

In article <[EMAIL PROTECTED]>, Ovid
<[EMAIL PROTECTED]> wrote:

> Note that the following does not trigger this:
> 
>   use UNIVERSAL::require;
>   use CGI qw;

CGI has the nifty feature of auto-generating functions from its import
list to turn them into HTML generating functions:

   use UNIVERSAL::require;
   use CGI qw;

   print no_such_function( "Hello" );

The output is:

   Hello

Re: UNIVERSAL::require broke my tests

[Rafael Garcia-Suarez]

Michael G Schwern wrote in perl.qa :
> There is a fix for this, something like changing UNIVERSAL::import to be...
>
> sub import {
> my($class) = shift;
>
> return unless $class eq 'UNIVERSAL';
>
>   ...do the export...
> }

Oh yes, that used to be a major *kh* problem.
That's what bleadperl's UNIVERSAL does, BTW.

-- 
* What system had proved more effective?
* Indirect suggestion implicating selfinterest.
-- Ulysses

Re: UNIVERSAL::require broke my tests

[Michael G Schwern]

Its not UNIVERSAL::require, its UNIVERSAL (which UNIVERSAL::require must
unfortunately load).

use UNIVERSAL;
use HTML::TokeParser qw(wibble);

HTML::TokeParser defines nor inherits any import routine.  When there's no
import, any arguments to use are ignored and any calls to Class->import are
ignored.

UNIVERSAL unfortunately imports import() from Exporter which means EVERYONE
has an import() routine.  Thus, boom.

There is a fix for this, something like changing UNIVERSAL::import to be...

sub import {
my($class) = shift;

return unless $class eq 'UNIVERSAL';

...do the export...
}

Re: UNIVERSAL::require broke my tests

[Ovid]

--- Ovid <[EMAIL PROTECTED]> wrote:

>   #!/usr/bin/perl 
> 
>   use strict;
>   use warnings;
> 
>   use UNIVERSAL::require;
>   use HTML::TokeParser qw;
> 
>   print "here";
> 
> That produces:
> 
>   :!perl -Ilib parse.pl
>   "no_such_function" is not exported by the HTML::TokeParser module
>   Can't continue after import errors at parse.pl line 7
>   BEGIN failed--compilation aborted at parse.pl line 7.
> 
> So it's great that I can now easily track this sort of error down,
> but it's not great that the code mysteriously stops working.

Note that the following does not trigger this:

  use UNIVERSAL::require;
  use CGI qw;

So I'm guessing it *might* be related to Exporter, but I don't have
time to track this down right now.

Cheers,
Ovid

--

Buy the book -- http://www.oreilly.com/catalog/perlhks/
Perl and CGI -- http://users.easystreet.com/ovid/cgi_course/

UNIVERSAL::require broke my tests

[Ovid]

This was *real fun* to track down.  Here's a minimal test case of what
was happening:

  #!/usr/bin/perl 

  use strict;
  use warnings;

  use HTML::TokeParser qw;

  print "here";

I run that and it prints 'here', even though HTML::TokeParser does not
export 'no_such_function'.  No errors or warnings produced.

Meanwhile, in code many modules away, UNIVERSAL::require is loaded and
my code goes boom!  Here's another minimal test case:

  #!/usr/bin/perl 

  use strict;
  use warnings;

  use UNIVERSAL::require;
  use HTML::TokeParser qw;

  print "here";

That produces:

  :!perl -Ilib parse.pl
  "no_such_function" is not exported by the HTML::TokeParser module
  Can't continue after import errors at parse.pl line 7
  BEGIN failed--compilation aborted at parse.pl line 7.

So it's great that I can now easily track this sort of error down, but
it's not great that the code mysteriously stops working.

Cheers,
Ovid

--

Buy the book -- http://www.oreilly.com/catalog/perlhks/
Perl and CGI -- http://users.easystreet.com/ovid/cgi_course/