[cgiapp] CGI::Application status update from the maintainer

[B. Estrade]

Thank you, Rhesa. This is helpful.

My last common on cgiapp_init and setup will be this. It's not simply
how deeply inheritance can be, it's the fact that there are 2 explicit
API methods for initializing an instance beyond what is provided for
in the ancestor.  For me, it'd make more sense to do a way with setup
altogether and use a method similar to the init hook you mentioned
below.  I am sure MMWV, but I will take your advice below. Thanks for
the help.

Brett

On Thu, Sep 6, 2012 at 12:04 PM, Rhesa Rozendaal <perl at rhesa.com> wrote:
> On 09/06/2012 04:48 PM, B. Estrade wrote:
>
>> You're limited to 2 generations below CAP if you want to subclass
>> without explicitly calling on SUPER because you have 2 explicit
>> methods -cgiapp_init and setup.  I am suggesting a way to provide any
>> number of generations without having to call on SUPER.
>
> You're not limited to 2 levels of inheritance. The grandchild's SUPER
> calls the child's method, and the child's SUPER calls the parent's
> method. It'll work the same even when you add a grandchild. (At some
> point I'd start asking myself if inheritance is really the way I'd want
> to structure my application).
>
>
>> Here is my real world use case.  I split my applications into 2 parts;
>> one amounts to the UI payload delivery, basically HTML that makes all
>> calls asynchronously. The other is strictly non-UI and handles only
>> asynchronous requests (i.e., the "REST" API). And I typically have
>> this hierarchy:
>>
>> 1. WebCommon.pm (ISA CGI::Application; implements Authentication and common run modes)
>> 2. WebApp.pm (ISA WebCommon; base class for the UI delivery or initial "view")
>> 3. WebAPI.pm (ISA WebCommon; base class for the "REST" API)
>>
>>>From there, I may have another or even another 2 levels of WebApps or
>> WebAPIs. In WebCommon.pm, I define cgiapp_init; in WebApps.pm and
>> WebAPI.pm, I define a setup. Beyond that, I redefine setup with a call
>> to $self->SUPER::setup - not something I really like doing.
>
>
> You'd be better off setting up your runmodes in an init hook. That's the
> way I do it in CA::Plugin::RunmodeDeclare.
>
> package WebCommon;
> use base 'CGI::Application';
>
> __PACKAGE__->add_callback( init => sub {
>      $_[0]->run_modes([ ... ]);
> });
>
> package WebAPI;
> use base 'WebCommon';
>
> __PACKAGE__->add_callback( init => sub {
>      $_[0]->run_modes([ ... ]);
> });
>
> package WebAPI::Stuff;
> use base 'WebAPI';
>
> __PACKAGE__->add_callback( init => sub {
>      $_[0]->run_modes([ ... ]);
> });
>
>
>
> Then WebAPI has all the run modes of WebCommon, as well as its own run
> modes. And WebAPI::Stuff has those of WebAPI and its own.
>
> However, I'd ask myself if I really want to have all those parent run
> modes in the child app.
>
>
>> I want to use CGI::Simple, but do not want to enable uploads app-wide.
>> I have a subclass (WebAPI::UploadApp, say) where I do want to enable
>> uploads.
>>
>> In WebCommon.pm, I have to do this:
>>
>> our $cgi; #= CGI::Simple->new;
>
> Don't do this. You need a query object that's an attribute of the
> current CA object. A package variable is going to have too wide a scope.
>
>> sub cgiapp_get_query {
>>      use CGI::Simple ();
>>      $cgi = CGI::Simple->new();
>>      return $cgi;
>> }
>
> This is better written as:
>
> sub cgiapp_get_query {
>      use CGI::Simple;
>      return CGI::Simple->new;
> }
>
>> Then in order to override that CGI::Simple to enable uploads, in
>> WebAPI::UploadApp, I have to do this:
>>
>> sub cgiapp_get_query {
>>      my $self = shift;
>>      use CGI::Simple ();
>>      $CGI::Simple::DISABLE_UPLOADS = 0;
>>      $self::SUPER::cgi             = CGI::Simple->new();
>>      return $self::SUPER::cgi;
>> }
>
> That code makes little sense. cgiapp_get_query is supposed to return a
> CGI compatible object. It's not supposed to change variables in another
> package.
>
> This is what you should do instead:
>
> sub cgiapp_get_query {
>      local $CGI::Simple::DISABLE_UPLOADS = 0;
>      return $_[0]->SUPER::cgiapp_get_query;
> }
>
>
>> Granted, there is probably a more correct, cleaner, or better way to do
>> this; if so, I am all ears.
>
> The only ugly thing about that is that package variable to influence
> upload behavior. It'd be prettier if CGI::Simple had an accessor for
> that, or a constructor argument. That's what you get for trying to be
> compatible with CGI.pm I guess ;)
>
> rhesa
>
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