Why does a module compile by itself but fail when used from elsewhere?

perl, perl-module

Solution

Edit (for posterity): Another reason for this to occur, and perhaps the most common reason, is that there is a circular dependency among the modules you are using.

Look in `Rebat/Store.pm` for clues. Your log says attempt to reload was aborted. Maybe `Rebat` already imports `Rebat::Store`, and `Rebat::Store` has some package-scope check against being loaded twice.

This code demonstrates the kind of situation I mean:

# m1.pl:
use M1;
use M1::M2;
M1::M2::x();

# M1.pm 
package M1;
use M1::M2;
1;

# M1/M2.pm
package M1::M2;
our $imported = 0;
sub import {
    die "Attempt to reload M1::M2 aborted.\n" if $imported++;
}
sub x { print "42\n" }
1;

$ perl m1.pl
Attempt to reload M1::M2 aborted.
BEGIN failed--compilation aborted at m1.pl line 3.

The code will compile (and print 42) if you just remove the `use M1::M2` line in `m1.pl`. In your case, you might not need to explicitly `use Rebat::Store` in your program.

Problem

I have a Perl module that appears to compile fine by itself, but is causing other programs to fail compilation when it is included: ``` me@host:~/code $ perl -c -Imodules modules/Rebat/Store.pm modules/Rebat/Store.pm syntax OK me@host:~/code $ perl -c -Imodules bin/rebat-report-status Attempt to reload Rebat/Store.pm aborted Compilation failed in require at bin/rebat-report-status line 4. BEGIN failed--compilation aborted at bin/rebat-report-status line 4. ``` The first few lines of `rebat-report-status` are ``` ... 3 use Rebat; 4 use Rebat::Store; 5 use strict; ... ```

Original source