# from Christopher J. Madsen
# on Saturday 15 March 2008 23:43:
>>This seems like it provides a lot of room
>> for subtle bugs. How would a plugin declare that it is incompatible
>> with another or otherwise avoid the silent error of "only one of my
>> plugins ran"?
>
>I don't think it would. That's up to the person selecting the plugins
>to run. Hopefully, user & system level plugins would be used only for
>things unlikely to conflict with other plugins.
It is still difficult to debug, regardless of hope or intent. If the
user breaks something via their config, a loud and obvious error should
result.
Similarly, maybe the priority should simply be by load-order. At least
then a plugin which knows it is incompatible with another can make
noise. Still it might be nice to have the noise created via some
mechanism in the registration (e.g. "conflicts => {Foo => '<= 0.2'}".)
>I don't think many pre hooks will need to short-circuit evaluation.
> But I think it needs to be possible to prevent the default method
> from being called. I suppose we could say that if a pre hook
> short-circuits, the remaining pre hooks are still called (but any
> values they try to return would be ignored) and only the default
> method gets skipped. But I'm not sure that's better.
Maybe the short-circuit (bypassing/replacing the default method) should
just be defined differently. That is: replace_METHOD() or something
and only allow one definition of it.
A few concrete examples would certainly help me work through that logic.
I suppose ACTION_code() or ACTION_dist() would be good examples. If
these are modifying files on disk, a bypass probably means that none of
the other hooks should run. Further, what are the pre and post hooks
typically doing in such a case?
When it comes to copying files, a cleaner scheme might be to install a
chain of filter subs which get each file and take/return a list of
lines. But that's quite a bit different than a hook which just e.g.
copies or generates some extra files or adds a depends().
--Eric
--
hobgoblin n 1: (folklore) a small grotesque supernatural creature that
makes trouble for human beings
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