Matt S Trout
dbix-class at trout.me.uk
Sat Feb 9 13:13:39 GMT 2008
On Fri, Feb 08, 2008 at 12:44:22PM +0000, nigel at turbo10.com wrote:
> Now trying to get things back on track ... I think roles will be really
> useful too as I often want to stuff things "sideways" into an OO
> inheritance hierarchy - but often the "ISA" relationship isn't quite
> right. Some objects just happen to "DO" the same thing -- which is where I
> think roles are handy.
"will be really useful" ?
Why future tense? http://search.cpan.org/perldoc?Moose gives you them right
now in straight perl5 ...
> But in relation to plugins I think it's tricky for roles to solve the
> whole problem. The problem is the plugin may represent only part of what
> needs to be added to the software - config setting changes may be required
> as well - also conflicts with other plugins need to be handled.
Well, for single-class plugins MooseX::Object::Pluggable seems to work
fairly well - the role mechanism can already flag conflicts although it
can't resolve them, and adding attributes (which can then be introspected
by MooseX::SimpleConfig or MooseX::Getopt) can be used to declare extra
The point at which it becomes trickier is when you need to subclass
related classes or add complex data as well; IOC can help make this sort
of thing more manageable but the code complexity cost annoys me. Anybody
with a good answer for how to generalise this approach onto a tree of
related classes/objects should speak up and I'll buy them beer as thanks :)
> Is it a pipe dream to imagine plugins slotting together cleanly like lego
> blocks? 
> I was reading about "monkeypatches" the other day  - and the idea of
> modifying running code in-situ offers a somewhat scary (from a security
> point of view) but different take on the problem of plugins working
> together. Installing a plugin is less like lego and more like applying a
> software bandaid --- did it stick? Ok let's put another one on. With the
> ability to take some off as well.
>  I think "webmin" has a brilliant module/plugin format
>  From wikipedia ... A monkey patch (also spelled monkey-patch,
> MonkeyPatch) is a way to extend or modify runtime code without altering
> the original source code for dynamic languages (e.g. Smalltalk,
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