[news.eclipse.platform] Re: No solution found because the problem in /tm

[Eric Rizzo <eclipse-news@xxxxxxxxxxxx>]

On 12/11/2008 1:57 PM, John J Barton wrote:
> Andrew Niefer wrote:
> > The problem is unsatisfiable means that p2 can't find a set of plugins
> > that satisfies all the requirements. If you look at the errors one at
> > a time, it really isn't that hard. (The hard part would be finding the
> > root cause).
>
> Thanks Andrew. ...
> > More non-overlapping version ranges, there are a bunch of these. And
> > this is probably the root cause. You are perhaps trying to install
> > something old into a 3.4.0 eclipse, and that old thing has
> > dependencies on a 3.2.0 eclipse.
>
> but what I was doing was installing something new -- a plugin I build
> with 3.4.1 eclipse update site thing -- in to 3.4.0 eclipse.
>
> My gut feeling is that the dependency analysis is just wrong. I assume
> it relies on information I gave to eclipse when I built my plugin, stuff
> in the manifest.mf? other places? But I have no idea what all that stuff
> means and frankly I don't want to know. How can I build my plugin to
> work with a given eclipse version? Somewhere I want to put "check
> against eclipse 3.4.0" and when users install I want the message to be
> either "success" or "you need eclipse 3.4.0". All that other stuff
> simply cannot be my users interface to my install.

First of all, it is not an option for you to be ignorant about 
dependencies and installation management if you're going to be a plugin 
publisher. It is just as important as understanding how to use SWT or 
what to do in your Activator start/stop methods, etc; it goes with the 
territory.

Now, if you want to target a particular version of particular plugins 
(remember, each plugin can be updated and change its version 
independently), you need to specify that in your plugins' Dependency 
list. For each plugin listed as a Dependency, you can (and should) 
specify a version range that is acceptable. Of course it is not a 
trivial matter, you have to think about the version ranges you want to 
allow: too restrictive and your stuff won't be compatible with arbitrary 
Eclipse instances; too loose and you'll get installed into environments 
that aren't really compatible with your code.
This is all part of designing a plugin or plugins - you have to think 
about what your target environment requirements are and embed that info 
into your plugin(s) dependencies and possibly your Feature definition.

Hope this helps,
Eric