Providers framework needs to be able to target specific consumers

[Dustin Spicuzza]

Providers in Exaile are pretty useful, but they currently are a bit limited. Currently, providers are all or nothing -- so there isn't a way to say 'only provide this service to a particular thing'.

A good example where this could be useful is with player enhancements. If I have an enhancement plugin that attaches to the player pipeline (say, to add an echo or something), when it registers a provider it will be added to *all* player objects that get created. However, what I really want is to only add the echo enhancement to a particular player object, and still be able to use the provider system to register other things for all players.

Another example would be with provider-based menus. You could use this functionality to ensure that a particular menu item is only applied to a particular widget, instead of all widgets -- while still retaining the ability for other menu items to be applied to all widgets if they so desire.

[Dustin Spicuzza (dustin-virtualroadside)]

FIxed in r4259, with ProviderMenu enhancements in r4260

[Dustin Spicuzza (dustin-virtualroadside)]

Note that the best way to go about this if we were starting from scratch is to force all provider consumers to pass themselves as a possible target, but that would be rather invasive. Instead, I opted to make targets optional, and only use this enhancement where needed, since it will usually not be used.

[Dustin Spicuzza (dustin-virtualroadside)]

This never made it into 3.3.x, targeting for 3.4.x instead.