Import Module/Function - Undefined subroutine

[Axel]

Dear All!

Since quite a while i am having pain with a module import issue.

Here i post 2 examples from which the first does not work.
It would be very nice if one could explain, why my first example
does not work. What do i need to do getting it working?

Thx a lot! Axel

1. example, 1xScript, 2xModul

Result:

(16:14:59) [2] ./test.pl
main company::show_company
Undefined subroutine &company::read_artist called at company.pm line
33 (#1)
(F) The subroutine indicated hasn't been defined, or if it was, it
has
since been undefined.

Uncaught exception from user code:
Undefined subroutine &company::read_artist called at
company.pm line 33.
at company.pm line 33
company::show_company() called at ./test.pl line 15

test.pl
##################

#!/usr/bin/perl

use warnings;
use diagnostics;
use strict;

use artist qw {
show_artist
};

use company qw {
show_company
};

show_company();

show_artist();

artist.pm
########################

package artist;

use warnings;
use diagnostics;
use strict;

use company qw {
read_company
};

use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK);

@ISA = qw(Exporter);
@EXPORT_OK = qw(
read_artist
show_artist
);

sub read_artist {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";
}

sub show_artist {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";

read_company();
read_artist();

print "Show Artist and the appendant Company...";
}

return(1);

company.pm
######################

package company;

use warnings;
use diagnostics;
use strict;

use artist qw {
read_artist
};

use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK);

@ISA = qw(Exporter);
@EXPORT_OK = qw(
read_company
show_company
);

sub read_company {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";
}

sub show_company {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";

read_artist();
read_company();

print "Show Company and the appendant artists...";
}

return(1);

##############################################################

2. example, 1xScript, 4xModul

Result:

(17:22:51) [3] ./test.pl
main company::show_company
company artist_read::read_artist
company company_read::read_company
Show Company and the appendant artists...
main artist::show_artist
artist company_read::read_company
artist artist_read::read_artist
Show Artist and the appendant Company...

test.pl
##################

#!/usr/bin/perl

use warnings;
use diagnostics;
use strict;

use artist qw {
show_artist
};

use company qw {
show_company
};

show_company();

show_artist();

artist.pm
########################

package artist;

use warnings;
use diagnostics;
use strict;

use company_read qw {
read_company
};

use artist_read qw {
read_artist
};

use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK);

@ISA = qw(Exporter);
@EXPORT_OK = qw(
show_artist
);

sub show_artist {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";

read_company();
read_artist();

print "Show Artist and the appendant Company...\n";
}

return(1);

company.pm
######################

package company;

use warnings;
use diagnostics;
use strict;

use artist_read qw {
read_artist
};

use company_read qw {
read_company
};

use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK);

@ISA = qw(Exporter);
@EXPORT_OK = qw(
show_company
);

sub show_company {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";

read_artist();
read_company();

print "Show Company and the appendant artists...\n";
}

return(1);

artist_read.pm
######################

package artist_read;

use warnings;
use diagnostics;
use strict;

use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK);

@ISA = qw(Exporter);
@EXPORT_OK = qw(
read_artist
);

sub read_artist {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";
}

return(1);

company_read.pm
######################

package company_read;

use warnings;
use diagnostics;
use strict;

use Exporter;
use vars qw(@ISA @EXPORT @EXPORT_OK);

@ISA = qw(Exporter);
@EXPORT_OK = qw(
read_company
);

sub read_company {
my ( $package, $filename, $line, $subroutine, $hasargs,
$wantarray, $evaltext, $is_require, $hints, $bitmask ) =
caller( 0 );

print STDOUT "$package $subroutine\n";
}

return(1);

[David Formosa (aka ? the Platypus)]

On Mon, 30 Nov 2009 08:53:32 -0800 (PST), Axel <axel.chr...@gmx.de> wrote:
> Dear All!
>
>
> Since quite a while i am having pain with a module import issue.
>
> Here i post 2 examples from which the first does not work.
> It would be very nice if one could explain, why my first example
> does not work. What do i need to do getting it working?

You have mutually recursive modules. (That is A uses B which uses A). Perl can run into
problems in situations like this. Best advice is to refactor your code so you don't have
a loop like this.