Package Foo;
use strict;
use Exporter;
use vars qw(@EXPORT_OK);
@EXPORT_OK = (&sysread);

sub sysread
  { print "this is not the real thing\n"; }

Package Bar;
use Foo qw(sysread);

print "about to test sysread\n";
sysread;
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What really dazzles me is not even the fact that it doesn't quite work the way I want it to, but that in fact both functions are being called on.

I know you requested no lectures, but the code you posted had some fundamental errors that make me wonder whether it is a good idea for you to be playing with fire. It's your business if you want to hang yourself, but I feel uneasy handing you the rope for it. I just had to get this off my chest. OK, end of sermonette.

I found at least three major errors in your code (more if all the code was intended to reside in a single file). The first one is that it's package, all lower case. What you wrote is equivalent to Foo->Package (see perlobj) . Next, it is not enough to use Exporter; you need to make your class a subclass of it. Like this:

package Foo;
use Exporter;
our @ISA = ( 'Exporter' );
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or (my preferred idiom):

package Foo;
use base 'Exporter';
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(There are more idioms for doing this; see perlobj). The third thing is that the entries in @EXPORT, @EXPORT_OK, etc. are supposed to be strings. Something like @EXPORT_OK = ( &frobozz ) will put the value returned by the frobozz subroutine (whatever that is) in @EXPORT_OK, which, unless frobozz is the rare function that narcissistically returns its own name, won't do you any good.

OK, so here's what you do:

# file Foo.pm

package Foo;
use strict;
use warnings;

use Exporter;
our @ISA       = ( 'Exporter' );
our @EXPORT_OK = ( 'sysread' );

sub sysread {
  warn "this is not the real thing\n";
}

1;
__END__

# file test.pl

use strict;
use warnings;

package Bar;
use Foo 'sysread';

warn "about to test sysread\n";
sysread;
__END__

% perl test.pl
about to test sysread
this is not the real thing
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Note that the code in the example above is split over two files; it won't work as written if you put it all in one file.

Definitely give a very good read or two to the relevant section of perlsub that I cited before.

the lowliest monk

indeed, a couple of nasty errors in there. Basically what I did was (rather too) quickly type in that part which was relevant, making some mistakes in the process. Typing Package instead of package is a habit I somehow managed to pick up and which, fortunately, my editor warns me about each time I make it. As for using strings, I didn't see anything about this in the documentation for Exporter, is this really a necessity?

Long story short, adding the @ISA=('Exporter'); line did in fact resolve the problem, many thanks :-)