Re: $meta->superclasses()

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You are setting the superclasses explicitly so you're not inheriting from =
Moose::Object which defines the hooks that call BUILDARGS.




-Chris

On Sat, Nov 21, 2015 at 2:07 PM, Bill Moseley <[email protected]> wrote:

> I need a bit of help understanding this code in Catalyst used for adding =
in
> Plugins:
>             my $meta =3D Class::MOP::get=5Fmetaclass=5Fby=5Fname($class);=

>             $meta->superclasses($plugin, $meta->superclasses);
> This is preventing BUILDARGS from running, and I'm not sure why.  Can
> someone provide an explanation=3F
> Thanks!
> A Catalyst app extends 'Catalyst', and Catalyst extends =
Catalyst::Component.
> <http://git.shadowcat.co.uk/gitweb/gitweb.cgi=3Fp=3Dcatagits/Catalyst-Run=
time.git;a=3Dblob;f=3Dlib/Catalyst.pm;h=3D7e563cb399229facdf7271c7506b294cb=
0b35fb3;hb=3DHEAD#l5>
> A Catalyst Component has a config *class* attribute and it also has a
> BUILDARGS
> <http://git.shadowcat.co.uk/gitweb/gitweb.cgi=3Fp=3Dcatagits/Catalyst-Run=
time.git;a=3Dblob;f=3Dlib/Catalyst/Component.pm;h=3D55f25c0092ec598d69484ba=
abe728a53db37af47;hb=3DHEAD#l89>
> method.  BUILDARGS merges in the component's *class* configuration into =
the
> instance arguments.
> In other words, the component's class configuration can populate the
> attributes each time the instance is created.
> The issue I'm seeing is for (non Moose::Role) plugins the code above is
> called and then BUILDARGS is no longer called and thus the config no =
longer
> sets attributes.
> The behavior of the app changes depending if loading non-Moose::Role
> plugins or not.
> So, I have three questions:
> First, is is incorrect for Catalyst to use =22sub BUILDARGS
> <http://git.shadowcat.co.uk/gitweb/gitweb.cgi=3Fp=3Dcatagits/Catalyst-Run=
time.git;a=3Dblob;f=3Dlib/Catalyst/Component.pm;h=3D55f25c0092ec598d69484ba=
abe728a53db37af47;hb=3DHEAD#l89>=22
> instead of using the =22around=22 method modifier=3F
> Second, why is Catalyst::Component::BUILDARGS no longer called once
>            $meta->superclasses($plugin, $meta->superclasses);
> is run=3F   Is there some other BUILDARGS now overriding=3F
> And third, I have included an example below of a Catalyst app that
> demonstrates the behavior above. That app includes a =22foo=22 attribute =
which
> is initialized by the configuration.
> Note that the =22foo=22 attribute has =22init=5Fargs =3D> undef=22.
> The =22foo=22 attribute is initialized when the =22MyPlugin=22 is =
commented out.
> Why is =22init=5Fargs =3D> undef=22 not preventing =22foo=22 from being =
initialized=3F
> Here's a simple script that shows the behavior.
> Moose-2.1604
> Catalyst-5.90103
> $ cat test.pl
> package Catalyst::Plugin::MyPlugin;
> use Moose;
> package Foo;  # A Catalyst app.
> use Moose;
> extends 'Catalyst';
> use Catalyst (
>     'MyPlugin',   # <---- comment out to see change
> );
> has foo =3D> (
>     is  =3D> 'ro',
>     init=5Farg =3D> undef,  # How is it that this attribute is ever =
set=3F
> );
> Foo->config(
>     foo =3D> { some =3D> 'hash' },
> );
> Foo->setup;
> before dispatch =3D> sub {
>     my $self =3D shift;
>     use Data::Dumper;
>     *# Show what the value of the attribute is now.*
>     *printf =22attribute foo is [%s]\n=22, Dumper $self->foo;*
>     die =22dead\n=22;
> };
> package main;
> use strict;
> use warnings;
> use Catalyst::Test 'Foo';
> request '/hello';
> Running with the MyPlugin I get:
> attribute foo is [$VAR1 =3D undef;
> ]
> Running w/o the plugin:
> attribute foo is [$VAR1 =3D {
>           'some' =3D> 'hash'
>         };
> ]
> What's also interesting is if I add this to the the Foo class then the
> =22foo=22 attribute is set even when the MyPlugin is included.
> before BUILDARGS =3D> sub {};
> --=20
> Bill Moseley
> [email protected]
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<div>You are setting the superclasses explicitly so you're not inheriting =
from Moose::Object which defines the hooks that call BUILDARGS.</div>
<div><br></div>
<div>-Chris</div>
<div class=3D=22mailbox=5Fsignature=22><br></div>
<br><br><div class=3D=22gmail=5Fquote=22><p>On Sat, Nov 21, 2015 at 2:07 PM=
, Bill Moseley <span dir=3D=22ltr=22>&lt;<a href=3D=22mailto:moseley@hank.=
org=22 target=3D=22=5Fblank=22>[email protected]</a>&gt;</span> =
wrote:<br></p><blockquote class=3D=22gmail=5Fquote=22 style=3D=22margin:0 0=
 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;=22><div><div =
dir=3D=22ltr=22>
<div>I need a bit of help understanding this code in Catalyst used for =
adding in Plugins:<br><br></div>
<div>
<div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 my $meta =3D =
Class::MOP::get=5Fmetaclass=5Fby=5Fname($class);</div>
<div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 $meta-&gt;superclasses($plug=
in, $meta-&gt;superclasses);</div>
</div>
<div><br></div>
<div>This is preventing BUILDARGS from running, and I'm not sure why.=C2=A0=
 Can someone provide an explanation=3F<br><br>Thanks!</div>
<div><br></div>
<div><br></div>
<div>A Catalyst app extends 'Catalyst', and Catalyst <a =
href=3D=22http://git.shadowcat.co.uk/gitweb/gitweb.cgi=3Fp=3Dcatagits/Catal=
yst-Runtime.git;a=3Dblob;f=3Dlib/Catalyst.pm;h=3D7e563cb399229facdf7271c750=
6b294cb0b35fb3;hb=3DHEAD#l5=22>extends Catalyst::Component.</a>
</div>
<div><br></div>
<div>A Catalyst Component has a config <i>class</i>=C2=A0attribute=C2=A0and=
 it also has a <a href=3D=22http://git.shadowcat.co.uk/gitweb/gitweb.=
cgi=3Fp=3Dcatagits/Catalyst-Runtime.git;a=3Dblob;f=3Dlib/Catalyst/Component=
.pm;h=3D55f25c0092ec598d69484baabe728a53db37af47;hb=3DHEAD#l89=22>BUILDARGS=
</a> method.=C2=A0 BUILDARGS merges in the component's <i>class</i> =
configuration into the instance arguments.</div>
<div><br></div>
<div>In other words, the component's class configuration can populate the =
attributes each time the instance is created.</div>
<div><br></div>
<div>The issue I'm seeing is for (non Moose::Role) plugins the code above =
is called and then BUILDARGS is no longer called and thus the config no =
longer sets attributes.</div>
<div><br></div>
<div>The behavior of the app changes depending if loading non-Moose::Role =
plugins or not.</div>
<div><br></div>
<div>So, I have three questions:</div>
<div><br></div>
<div>First, is is incorrect for Catalyst to use =22<a href=3D=22http://git.=
shadowcat.co.uk/gitweb/gitweb.cgi=3Fp=3Dcatagits/Catalyst-Runtime.=
git;a=3Dblob;f=3Dlib/Catalyst/Component.pm;h=3D55f25c0092ec598d69484baabe72=
8a53db37af47;hb=3DHEAD#l89=22>sub BUILDARGS</a>=22 instead of using the =
=22around=22 method modifier=3F</div>
<div><br></div>
<div><br></div>
<div>Second, why is Catalyst::Component::BUILDARGS no longer called =
once</div>
<div><br></div>
<div>=C2=A0=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 $meta-&gt;superclasses($plugi=
n, $meta-&gt;superclasses);<br></div>
<div><br></div>
<div>is run=3F =C2=A0 Is there some other BUILDARGS now =
overriding=3F</div>
<div><br></div>
<div><br></div>
<div>And third, I have included an example below of a Catalyst app that =
demonstrates the behavior above. That app includes a =22foo=22 attribute =
which is initialized by the configuration.</div>
<div><br></div>
<div>Note that the =22foo=22 attribute has =22init=5Fargs =3D&gt; undef=22.=
</div>
<div><br></div>
<div>The =22foo=22 attribute is initialized when the =22MyPlugin=22 is =
commented out.</div>
<div><br></div>
<div>Why is =22init=5Fargs =3D&gt; undef=22 not preventing =22foo=22 from =
being initialized=3F</div>
<div><br></div>
<div><br></div>
<div>Here's a simple script that shows the behavior. =C2=A0</div>
<div><br></div>
<div>Moose-2.1604<br></div>
<div>Catalyst-5.90103</div>
<div><br></div>
<div><font face=3D=22monospace, monospace=22>$ cat <a href=3D=22http://test=
.pl=22>test.pl</a></font></div>
<div><font face=3D=22monospace, monospace=22>package =
Catalyst::Plugin::MyPlugin;<br></font></div>
<div>
<div><font face=3D=22monospace, monospace=22>use Moose;</font></div>
<div><br></div>
<div><font face=3D=22monospace, monospace=22>package Foo; =C2=A0# A =
Catalyst app.</font></div>
<div><font face=3D=22monospace, monospace=22>use Moose;</font></div>
<div><font face=3D=22monospace, monospace=22>extends =
'Catalyst';</font></div>
<div><font face=3D=22monospace, monospace=22>use Catalyst (</font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 'MyPlugin', =
=C2=A0 # &lt;---- comment out to see change</font></div>
<div><font face=3D=22monospace, monospace=22>);</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>has foo =3D&gt; =
(</font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 is =C2=A0=3D&gt;=
 'ro',</font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 init=5Farg =
=3D&gt; undef, =C2=A0# How is it that this attribute is ever =
set=3F</font></div>
<div><font face=3D=22monospace, monospace=22>);</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>Foo-&gt;config(</font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 foo =3D&gt; { =
some =3D&gt; 'hash' },</font></div>
<div><font face=3D=22monospace, monospace=22>);</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>Foo-&gt;setup;</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>before dispatch =3D&gt; sub =
{</font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 my $self =3D =
shift;</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 use =
Data::Dumper;</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 <b># Show what =
the value of the attribute is now.</b></font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 <b>printf =
=22attribute foo is [%s]\n=22, Dumper $self-&gt;foo;</b><br></font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>=C2=A0 =C2=A0 die =
=22dead\n=22;</font></div>
<div><font face=3D=22monospace, monospace=22>};</font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22><br></font></div>
<div><font face=3D=22monospace, monospace=22>package main;</font></div>
<div><font face=3D=22monospace, monospace=22>use strict;</font></div>
<div><font face=3D=22monospace, monospace=22>use warnings;</font></div>
<div><font face=3D=22monospace, monospace=22>use Catalyst::Test =
'Foo';</font></div>
<div><br></div>
<div><br></div>
<div>request '/hello';</div>
</div>
<div><br></div>
<div>Running with the MyPlugin I get:</div>
<div><br></div>
<blockquote style=3D=22margin:0px 0px 0px 40px;border:none;padding:0px=22>
<div><div>attribute foo is [$VAR1 =3D undef;</div></div>
<div><div>]</div></div>
</blockquote>
<div><br></div>
<div>Running w/o the plugin:</div>
<div><br></div>
<blockquote style=3D=22margin:0px 0px 0px 40px;border:none;padding:0px=22>
<div><div>attribute foo is [$VAR1 =3D {</div></div>
<div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 'some' =3D&gt; =
'hash'</div></div>
<div><div>=C2=A0 =C2=A0 =C2=A0 =C2=A0 };</div></div>
<div><div>]</div></div>
</blockquote>
<div><br></div>
<div><br></div>
<div>What's also interesting is if I add this to the the Foo class then the=
 =22foo=22 attribute is set even when the MyPlugin is included.</div>
<div><br></div>
<div>before BUILDARGS =3D&gt; sub {};<br></div>
<div><br></div>
<br clear=3D=22all=22><div><br></div>-- <br><div>Bill Moseley<br><a =
href=3D=22mailto:[email protected]=22>[email protected]</a>
</div>
</div></div></blockquote></div><br>
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