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Postings from March 2022
On 3/13/22 15:08, Diab Jerius via module-authors wrote:
> On 3/13/22 16:13, David Christensen wrote:
>> module-authors:
>>
>> I have been wrestling with the Exporter module and subroutine circular
>> dependencies between modules for a number of years. I have yet to
>> find a satisfactory solution.
> If you move import of modules with circular dependencies to runtime
> rather than compile time:
>
>
> $ diff Exporter-circular-use{.orig,.new}
> diff Exporter-circular-use.orig/Bar11.pm
> Exporter-circular-use.new/Bar11.pm
> 13c13,14
> < use Foo11;
> ---
> > require Foo11;
> > Foo11->import;
> diff Exporter-circular-use.orig/Foo11.pm
> Exporter-circular-use.new/Foo11.pm
> 13c13,14
> < use Bar11;
> ---
> > require Bar11;
> > Bar11->import;
>
>
> $ perl Exporter-circular-use.t
> ok 1 - foo00
> ok 2 - foo01
> ok 3 - foo10
> ok 4 - foo11
> 1..4
Thank you for the reply. :-)
Yes, that works.
> Or move the export completely into compile time:
>
> $ diff Exporter-circular-use{.orig,.new}
> diff Exporter-circular-use.orig/Bar11.pm
> Exporter-circular-use.new/Bar11.pm
> 9,11c9,11
> < require Exporter;
> < our @ISA = qw( Exporter );
> < our @EXPORT = qw( bar );
> ---
> > use parent 'Exporter';
> > our @EXPORT;
> > BEGIN{ @EXPORT = qw( bar ); }
> diff Exporter-circular-use.orig/Foo11.pm
> Exporter-circular-use.new/Foo11.pm
> 9,11c9,11
> < require Exporter;
> < our @ISA = qw( Exporter );
> < our @EXPORT = qw( foo );
> ---
> > use parent 'Exporter';
> > our @EXPORT;
> > BEGIN { @EXPORT = qw( foo ); }
Yes, that also works. Putting the @EXPORT allocation and initialization
in a BEGIN block ahead of the 'use parent' looks even better:
2022-03-13 18:15:46 dpchrist@tinkywinky
~/samba/dpchrist/sandbox/perl/Exporter-circular-use
$ diff Foo11.pm Foo33.pm
1c1
< package Foo11;
---
> package Foo33;
9,11c9,10
< require Exporter;
< our @ISA = qw( Exporter );
< our @EXPORT = qw( foo );
---
> BEGIN { our @EXPORT = qw( foo ) }
> use parent 'Exporter';
13c12
< use Bar11;
---
> use Bar33;
David
2022-03-13 18:38:24 dpchrist@tinkywinky
~/samba/dpchrist/sandbox/perl/Exporter-circular-use
$ cat /etc/debian_version ; uname -a ; perl -v | head -n 2
9.13
Linux tinkywinky 4.9.0-17-amd64 #1 SMP Debian 4.9.290-1 (2021-12-12)
x86_64 GNU/Linux
This is perl 5, version 24, subversion 1 (v5.24.1) built for
x86_64-linux-gnu-thread-multi
2022-03-13 18:40:00 dpchrist@tinkywinky
~/samba/dpchrist/sandbox/perl/Exporter-circular-use
$ ./Exporter-circular-use.t
ok 1 - foo00
ok 2 - foo01
ok 3 - foo10
Undefined subroutine &Bar11::foo called at Bar11.pm line 22.
not ok 4 - foo11
# Failed test 'foo11'
# at ./Exporter-circular-use.t line 24.
# got: 'main=7
# foo=6
# bar=5
# '
# expected: 'main=7
# foo=6
# bar=5
# foo=4
# bar=3
# foo=2
# bar=1
# '
Undefined subroutine &Bar12::foo called at Bar12.pm line 23.
not ok 5 - foo12
# Failed test 'foo12'
# at ./Exporter-circular-use.t line 24.
# got: 'main=7
# foo=6
# bar=5
# '
# expected: 'main=7
# foo=6
# bar=5
# foo=4
# bar=3
# foo=2
# bar=1
# '
ok 6 - foo21
ok 7 - foo22
ok 8 - foo33
1..8
# Looks like you failed 2 tests of 8.
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