Re: Obscure baffling "module not exported" error: can someone help me find the cause?

On Jan 31, 12:20 pm, Henry Law <n...@xxxxxxxxxxxxx> wrote:


(snipped)


Now for the description of the code itself, which is a bit involved,
despite my having condensed it down to its bare essentials. If you're
prepared to help me make sense of this thenhttp://www.lawshouse.org/perl/Problem.jpgshows the thing
diagrammatically, with arrows drawn on. You can just about read the code
in the image too.

There are three modules: NFBT::ServerLib, NFBT::Utilities::Common and
NFBT::Utilities::Server. There is some requirement in them for
subroutines out of one or more of the others.


(snipped)

First of all, you have a couple of modules that mutually use
each other, namely:

NFBT::ServerLib and
NFBT::Utilities::Server

this is generally a bad idea and you should consider refactoring;
see the discussion here:

http://www.perl.com/pub/a/2000/07/p5pdigest/THISWEEK-20000709.html#Mutual_use

Remember that use statements are collected into the BEGIN block (even
if
you embed them inside a subroutine) to be evaluated at compile-time
-- see 'perldoc perlmod'.

So, I'd suggest that you refactor. A quick "work-around" would be
that
in NFBT::Utilities::Server, you change

use NFBT::ServerLib

to

require NFBT::ServerLib;
import ServerLib (qw/write_xml_twig/);

in which case:

#!/usr/bin/perl
use strict;
use warnings;
use NFBT::Utilities::Server qw ( shadow_conv );

print "This is the test routine $0\n";
shadow_conv();

ought to run as expected (because 'require', unlike 'use'
is evaluated at run-time).

--
Hope this helps,
Steven
.