Nested Modules in perl

[gjoshi]

Hi all,

I have couple of perl modules like connectivity.pm, ipc.pm, ue.pm, db.pm, general.pm

All these modules have functions according to their functionality.

Now there are certain modules call each other like connectivity.pm calls db.pm and db.pm calls connectivity.pm functions.

Now I can't call use db in connectivity and use connectivity in db.pm. It gives me error predefined and if I don't call then i am getting function missing error.

Could you please tell me how to achieve this kind of scenario?

thanks --girija

[MidLifeXis]

I believe that you are asking the question "If I have packages A and B, and A calls stuff from B (say, B::x()) and B calls stuff from A (say A::y()), how can I break up the circular dependency?"

If this is a correct restatement of your question, create module C containing C::x() and C::y(), and have A and B require C, calling C::x() and C::y() instead.

Often, when I see this crop up in my code, I have tried to include something in a module that does not belong that should be factored out into a separate module.

[Laurent_R]

Hi gjoshi,

I have Mod2.pm:

#!/usr/bin/perl -w

package Mod2;

use strict;
use warnings;
use Mod3;

require Exporter;

our $VERSION = '0.1000';
our @ISA = qw/Exporter/;
our @EXPORT_OK = qw (double sixtimes);

sub double { return 2 *shift}
sub sixtimes {
    my $val = double shift;
    return Mod3::triple($val);
}

And Mod3.pm:

#!/usr/bin/perl -w

package Mod3;

use strict;
use warnings;
use Mod2;

require Exporter;

our $VERSION = '0.1000';
our @ISA = qw/Exporter/;
our @EXPORT_OK = qw (triple fourtimes);

sub triple { return 3 * shift}
sub fourtimes {
    my $val = Mod2::double(shift);
    return Mod2::double($val);
}

And my user program (usemod.pl) is as follows:

#!/usr/bin/perl

use feature qw /say/;
use strict;
use warnings;
use Mod2 qw /sixtimes/;
use Mod3 qw /triple fourtimes/;

for my $x (0..4) {
    say "$x * 3 = ", triple($x);
    say "$x * 6 = ", sixtimes($x);
    say "$x * 4 = ", fourtimes($x);
    say "$x * 6 * 4 = ", sixtimes (fourtimes($x));
}

This seems to work fine:
Read more... (454 Bytes)

Or did I miss something in your question?

[Monk::Thomas]

Please show code. Strip down some of your modules to the minimum functionality required to trigger the error and post the code.

[AnomalousMonk]

See also the Short, Self Contained, Correct (Compilable), Example.

[vinoth.ree]

Hi gjoshi,

Please post us the exact error + the code you are trying so that we can help you better.

Read: How do I post a question effectively?

[gjoshi]

Hi all, as MidLifeXis was saying I am trying to do same thing. Here is my code: Module Connectivity.pm

use MyDB;

our @ISA = qw(Exporter);
our @EXPORT = qw(ConnectSsh SendAndGet_Cmd);

sub ConnectSsh
{
   #connect to shell
   #writes to DB
   WriteValueToDB ($text)
}

sub SendAndGet_Cmd
{
   my ($cmd) = @_;
   #sends commands over shell handle
}

1;

MyDB.pm

our @ISA = qw(Exporter);
our @EXPORT = qw(EndRub WriteValueToDB );

sub EndRub
{
   #send close command
   $op = SendAndGet_Cmd($test);
   #add status to DB
   WriteValueToDB ($op);
}

sub WriteValueToDB
{
   my ($test) = @_;
   
   #write to DB
    ...
    ....
    ....
}



1;

Now you see both are dependent on each other. So if I am getting error declaration is already done.