Re: [cgiapp] Re: RFC - C::A::Plugin - abstract base class for plugins

[Michael Peters <suppressed>]

Bill Catlan wrote:
> Hi Cees,
>
> Thank you for the thorough response.  I thought of the
> problem you mention, but not so much from the "rug
> being pulled out from under you in mod_perl" angle. 
> Still, the issue is the same - namespace collision. 
> I'm not sure I can propose the best solution without
> some more thought.  However, you can still have
> namespace collisions between plugins brought into an
> app module, which is not desirable and which I propose
> should be solved now.  Thus, if we need to solve the
> namespace problem, we should solve it and use the
> approach that brings the plugin into C::A, since it is
> a C::A plugin.

Why do we need to put things into C::A's namespace? I 
thought they just showed that this is a bad idea. Even if we 
implement 'register-unregister' system, you're every 
application running cgiapp on a mod_perl server could be 
ruined if *one* programmer forgot to unregister his plugin. 
And not just til he fixes it, but until the server get's 
rebooted. I think that's a very bad situation to even allow 
to happen.

I think the only save way to import these methods into any 
namespace is to put them into the app's namespace wich is 
using it. Anything else will cause problems.

You're right, this does leave a problem with one plugin's 
methods overriding anothers. I can't think of a good way to 
solve this unless we ask that each method be descriptive. 
Like Cees's 'tt_process()' method (for 
CGI::Application::Template) instead of just 'process'.

Or we could try to introduce an intermediary namespace 
chosen by the user to access the methods. Maybe something 
like this...

    package MyApp;
    use base 'CGI::Application';
    use CGI::Application::Plugin::Foo qw(name => foo);

    [snip]

    #call foo_stuff() that comes from C::A::P::Foo plugin
    $self->plugins{foo}->foo_stuff;


I don't particularly like that idea since it makes it more 
complicated, but at least it would solve namespace 
collisions cause the user using the plugin could name it 
whatever he wants.


--
Michael Peters
Developer
Plus Three, LP


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