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

UPD: all true, except the thing which reload modules in dev mode was not Catalyst's but our code, which simply "do $modulefile".

I am running Catalyst in dev mode. It's able to reload packages when package's file modified.

One of my packages:

package SRS::MyTest;
use parent 'File::Find';
our @ISA;
BEGIN { print STDERR "HEREISIT @ISA\n"};

1;

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If i modify it, catalyst will reload it, and then I see in console:

HEREISIT File::Find File::Find
 - /somepath/MyTest.pm reloaded 2343

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That means File::Find is now twice in @ISA. Not a big problem until you use MRO C3

With mro C3 it fails with error: "Inconsistent hierarchy during C3 merge of class"

I believe these are separate part of this problem:

PoC of problem without catalyst:

$ cat s1.pl
package XXX;
BEGIN { require mro; mro::set_mro( "XXX", 'c3' ); }
use parent qw( File::Find );
use parent qw( File::Find );
1;

$ perl s1.pl 
Inconsistent hierarchy during C3 merge of class 'XXX':
    current merge results [
        XXX,
    ]
    merging failed on 'File::Find' at /usr/share/perl/5.14/parent.pm l
+ine 26.
BEGIN failed--compilation aborted at s1.pl line 4.

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Questions are:

Replies are listed 'Best First'.
Re: Catalyst reload, 'use parent' and mro c3
by Anonymous Monk on Dec 23, 2015 at 19:35 UTC
    Probably just clear @ISA manually? 
    package SRS::MyTest;
our @ISA;
BEGIN { @ISA = (); }
use parent 'File::Find';
BEGIN { print STDERR "HEREISIT @ISA\n"};

1;

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    Where Catalyst's reloading code is described (or how to see it)?
    Don't know about Catalyst, but it's probably something like: 
    delete $INC{'XXX.pm'};
require 'XXX.pm';

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    in fact: 
    # main.pl
use XXX ();
delete $INC{'XXX.pm'};
require 'XXX.pm';

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    # XXX.pm
package XXX;
use parent 'File::Find';
our @ISA;
BEGIN { print STDERR "HEREISIT @ISA\n"};

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    that does just that 
    $ perl main.pl
HEREISIT File::Find
HEREISIT File::Find File::Find

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[reply]
[d/l]
[select]
      Probably just clear @ISA manually?
      Yes, that would work. Sad that I should insert this line too all of hundreds of files.
[reply]
        Well, you can fix parent.pm instead... it's a very simple module: 
        package parent;
use strict;
use vars qw($VERSION);
$VERSION = '0.232';

sub import {
    my $class = shift;

    my $inheritor = caller(0);

    if ( @_ and $_[0] eq '-norequire' ) {
        shift @_;
    }
    else {
        for ( my @filename = @_ ) {
            if ( $_ eq $inheritor ) {
                warn
                  "Class '$inheritor' tried to inherit from itself\n";
            }

            s{::|'}{/}g;
            require "$_.pm";    # dies if the file is not found
        }
    }

    {
        no strict 'refs';
        my %ISA = map { $_ => 1 } @{"$inheritor\::ISA"};
        for (@_) {
            push @{"$inheritor\::ISA"}, $_
              if not $ISA{$_};
        }
    };
}

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        just put it somewhere in @INC before the standard one, and let us know if it works :)
[reply]
[d/l]
[select]

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