Can you demonstrate the problem with a short piece of code. It's easier to follow code than narrative descriptions. Your description is a little unclear.

My first guess is that you need to also "require" the second program in the class that creates the object that you are talking about. But my second thought is that if this function is as useful as you think it is, then you should consider putting it into a real module which will make it easier to use elsewhere.

Maybe if you show us the relevant code, we can help you better.

I suggest that you reduce both, your main program and your module to the minimal code that still reproduces the problem and then post these two.

The error message you got

Undefined subroutine &hc_url::call_httpd_exec called at /exlibris/meta
+lib/m4_b/d
+at01/vir_ext/hc_url.pm line 166.
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tells you that the routine call_httpd_exec was looked up in package hc_url, which is not what you expected - not in package demo nor in package demo2.

Read perltoot.

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

The error message:

Undefined subroutine &hc_url::call_httpd_exec called at /exlibris/meta
+lib/m4_b/d
+at01/vir_ext/hc_url.pm line 166.
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is for my real program. The error code for my demo programs is :

Undefined subroutine &wrapper::call_httpd_exec called at demo.pm line 
+8.
[download]

hc_url isn't used. Does this change your answer?

Yes, the part w/regard to the error message changes.

You do a require "wrapper" in package demo and in package demo2. demo2 is used by demo. The use means, that demo2 is compiled and executed before demo is even compiled to end.

The docs for require state, that require doesn't include a file twice.

So, wrapper is already loaded via demo2, so it lives in demo2. The require in demo just returns 1, no file is loaded. You'll see that your code works if you change call_httpd_exec in demo to demo2::call_httpd_exec.

<update>
OTOH, if you wrap require "wrapper" in demo into a BEGIN block and place it before use demo2, then the call to call_httpd_exec will fail in demo2, since it now lives in demo.

Read require, use, again perltoot, perlmod, there BEGIN , CHECK, INIT and END... there are also modules which implement automatic exportation of functions, e.g. Spiffy.
</update>

--shmem

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}

#!/exlibris/metalib/m4_b/product/bin/perl
use demo;
{
    my $externalObject = new demo;
}
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package demo;
require "wrapper";
use demo2;
sub new {
        my $class  = shift;
        my $params = shift;
        my $self = {};
        &call_httpd_exec();
        my $externalObject2 = new demo2;
}
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package demo2;
require "wrapper";
sub new {
        my $class  = shift;
        my $params = shift;
        my $self = {};
        &call_httpd_exec();
}
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sub call_httpd_exec{
    print "hello world!!\n"
}

1;
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Undefined subroutine &demo::call_httpd_exec called at demo.pm line 8.
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---You are mixing 'require' with 'use', is there a reason for that? I am using both "require" and "use" programs in this case. I'm not sure what you mean about mixing them up. ---That is not necessary if called as a method (using the -> convention) or direct, using wrapper::call_httpd_exec I used wrapper::call_httpd_exec in my program but still recieved the same error message. Any ideas?

Not directly germane to the problem (I don't think at least; not that it's very clear what the problem is . . .), but Perl convention is to use Capitalized names for modules; lower cased names are reserved for language use.