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Re: [cross-project-issues-dev] dependencies, build and P2

> Gunnar Wagenknecht <gunnar@xxxxxxxxxxxxxxx>
> Am 19.12.2010 09:19, schrieb Eike Stepper:
> > I see that there are plugin and feature dependencies possible. Would
> > you say that the plugin dependcies are a relict from times before p2?
>
> Frankly, I'm constantly asking myself the same question. They definitely
> existed before p2. As far as I remember the old update manager used
> those dependencies. p2 should't need them as it is capable of collecting
> all the dependencies by using the meta-data produced from the bundle
> manifests.

Requirements expressed in feature.xml are mostly a relic from the era before p2. Old Update Manager only used the data in the feature.xml to resolve dependencies, so all dependencies had to be expressed at both the feature and bundle levels.  As Gunnar says, this redundancy is not needed with p2. There are still some cases where you require a feature or bundle, but do *not* have any bundle-level dependency on it. For example, a dependency on documentation might be expressed this way. In all other cases, you can remove the feature-level dependency altogether and rely on the bundle-level dependency pulling in what you need. There is some discussion of this in the version numbering guidelines [1]

Feature inclusions are a different matter. They are useful for locking down a precise "line up" of bundles that have been tested and verified to work together. This way you can ensure that future builds and installs of such features produce a consistent result, rather than being a function of what's available in the repository at the moment of build or install.

[1] http://wiki.eclipse.org/Version_Numbering#To_require_features_or_to_require_bundles

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