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

[Cees Hek <suppressed>]

Quoting Bill Catlan <suppressed>:

> Should C::A::Plugin perhaps put the plugin methods
> into C::A space, and not the C::A app module?  After
> all, the plugin is a /C::A/ plugin, not a 'MyApp'
> plugin.

Hi Bill,

That is how the C::A::Session module currently does it.  But there are some
concerns with this approach, especially when working in a shared environment
like mod_perl.  There could be multiple application running on the webserver
that all use CGI::Application.  Once one of them loads a plugin, those methods
would be visible to all applications.  Some would consider that a benefit, but
it has the potential to cause problems.

As a quick example of a problem that could arise.  Lets say I have an AUTOLOAD
method in my app, and I am looking to capture calls to a method called
'session'.  My app runs fine, until someone installs another application that
uses C::A::Session.  This now adds a 'session' method to CGI::Application, and
now all the sudden my app is broken, as my AUTOLOAD no longer traps the call to
'session', since there is now a real 'session' method in CGI::Application.

Or to change the example slightly, say I wrote my own session module, and stuck
a use base qw(CGI::Application My::Session::Module) in my app.  Everything works
fine until someone else uses C::A::Session and things start to break in my app.

Those examples may be a little contrived, but the possibilities are real.

This isn't an issue when working with a plain CGI script, or commandline script,
but can cause problems in persistent environments like mod_perl and SpeedyCGI
where you have multiple applications loaded at the same time that could be doing
wildly different things.

Cheers,

Cees

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