how to pass filehandle between module ?

bh_perl has asked for the wisdom of the Perl Monks concerning the following question:

i have main perl program called main.pl. The program will called openfile module to open/create new output file and writefile module to write contents into output files.

But how could i write all the contents into output files in writefile module ?. My sample program as below:

This is MAIN.PL

#!/usr/bin/perl

use lib '/tmp/bh';

use openFile qw/openfile/;
use writeFile qw /writefile/;

openfile;
writefile;
close (TEST);
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This is openfile module

package openFile;

use base 'Exporter';
our @EXPORT_OK = qw/openfile/;

sub openfile {
        open (TEST, ">/tmp/bh/output/test.txt");
        print (TEST "FILE HEADER\n");
}

1;
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This is writefile module

package writeFile;

use base 'Exporter';
our @EXPORT_OK = qw/writefile/;

sub writefile {
        printf (TEST "This is for testing only\n");
}

1;
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Re: how to pass filehandle between module ?
by Athanasius (Archbishop) on May 11, 2013 at 02:52 UTC

It is possible to do what you want by making TEST a package-scope variable within package openFile and then exporting it. (You would also need to export an openFile::close() subroutine to call in place of close (TEST).)

But this is a poor design. Much better to put all the file opening, writing, and closing routines together into a single package, e.g. package MyFile, and keep the details of the filehandle variable (in this case, MyFile::TEST) private to the package (i.e., unexported).

The general rule of modularisation is: Group related things together and keep independent things separate. In this case, opening and writing to the file are closely related activities and should be implemented within the same package.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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Re: how to pass filehandle between module ?
by vsespb (Chaplain) on May 11, 2013 at 13:40 UTC

open my $f, ">", $filename;
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Indirect filehandles in perlopentut

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Re: how to pass filehandle between module ? (like a variable)
by Anonymous Monk on May 11, 2013 at 08:11 UTC

Filehandles are variables, so to pass a filehandle between modules, pass it like a variable, see perlintro for the details

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