import not found

[rovf]

I was using a module Project::Config without problems, which had this structure:

package Project::Config;
use warnings FATAL => qw(all);
use strict;
use Exporter;
our @ISA='Exporter';
our @EXPORT_OK=qw(....);
...
sub AUTOLOAD {...}
INIT {...}

In one application, I wanted to replace the

use Project::Conifg;

by an explicit BEGIN { require .... import .... } sequence, and I wrote it like this:

package MyApp;
use strict;
use warnings;

# This had worked before:
# use Project::Config qw(foo bar);

# New code which does not work:
BEGIN {
  require 'Project/Config.pm';
  Project::Config::import(qw(foo bar));
}

It turned out that the call of the import function triggered Project::Config::AUTOLOAD(), i.e. as if no import were defined. I had expected that by compiling Config.pm, the Exporter would inject an import() method. Any idea why this failed?

[tilly]

Exporter does not inject a function, instead you inherit from it and the method call to import is supposed to resolve. When you call Project::Config::import(qw(foo bar)); you're not making a method call, so you don't search your inheritance tree and find Exporter. Change that line to Project::Config->import(qwfoo bar)); and things should improve.

Incidentally most things people do with AUTOLOAD are better done by other means. (In my experience, usually by assigning a bunch of closures to functions into the current package.) AUTOLOAD is a sledgehammer that can make code more brittle than it should be. With no context I don't know whether that is true in your case.

[ikegami]

Exporter does not inject a function

It does if you use

use Exporter qw( import );

instead of

use Exporter qw( );
our @ISA = 'Exporter';

But you still need to call it as a method.

[rovf]

Thanks a lot for the explanation!

AUTOLOAD is a sledgehammer that can make code more brittle than it should be. With no context I don't know whether that is true in your case.

I start to believe that it is true in my case...

[tilly]

Incidentally a random tip. If you want Exporter to inject a function into your space you can

use Exporter qw(import);

rather than inheriting from Exporter.

[Anonyrnous Monk]

I had expected that by compiling Config.pm, the Exporter would inject an import() method

It doesn't.  When you use @ISA='Exporter', the method would be looked up via inheritance.  But you can alternatively directly import Exporter's import method into your package:

use Exporter 'import';

Also, you probably wanted to call import as a method, i.e. using the arrow notation:

  Project::Config->import(qw(foo bar));

[JavaFan]

The right way would be to call

Project::Config->import(qw(foo bar));