Sorry for these troubles :-( Some of these are due to Eclipse's install
concept (which is well known as one of its weakest point), some will
probably have to do with bugs on our side.
> I tried to upgrade tonight to the latest version of your plugin. I
> met with great difficulty. First I told Eclipse to update the
> plugin. After eclipse had restarted I was given a class not found
> exception when loading any haskell project. So next I looked for a
> way to uninstall the plugin. I couldn't find one, but some plugins
> say you can just delete them from the plugins directory. I tried
> that, but eclipse wouldn't acknowledge the plugin was gone. So
> whenever I tried to update the plugin eclipse would tell me it was at
> the latest version.
That's a common problem about installing Eclipse plugins (unfortunately
:-(. Maybe I should give a bit of background here: In earlier versions
of Eclipse (pre-3.0, that is, until about 1 2/2 years ago) you would
install a plugin by just extracting it into the plugins/ folder of your
Eclipse installation. When restarting Eclipse, it would scan that
directory and install everything new that it found and remove what was
no longer there.
That story was abandoned with the Eclipse 3.0 release, mostly because
that way of 'installing' doesn't scale (long startup times) and it is
not manageable for users to remember which plugin does what and which
depends on which others. So they introduced the concept of 'features',
which are similar to packages in any package manager. Features must be
installed via the Update UI in Eclipse (Help > Software Updates > Find
new Features to install), and they can be uninstalled (Help > Software
Updates > Manage Configuration). As long as one doesn't fiddle with the
contents of the install folder, that story in itself is consistent.
Now the trouble is that they still somehow support the old way: you can
still extract plugins into the plugins/ folder. Sometimes Eclipse would
recognize them, sometimes not. You can force Eclipse to re-read all the
information by running it (once) with the -clean option. (Which isn't
more than a workaround, to be sure, but it may help with some problems
like the one you encountered when you had removed the plugins manually
:-) So the old way works still enough so that many projects around
didn't bother to support the new way (which is not terribly much work,
but involves a bit more maintainance).
As for uninstalling: Given a plugin was installed via the Update UI, it
can be uninstalled the following way: Help > Software Updates > Manage
Configuration; in that dialog, navigate to the feature. From the context
menu, you can now 'disable' it (you have to disable a feature before you
can uninstall it, don't ask me why ;-). Probably Eclipse wants to
restart then. After the restart, go to the same dialog, select from the
toolbar the 'Show disabled features' button, then you see the disabled
feature again in the tree. Now you can uninstall it from the context menu.
In this 'Manage configuration' dialog, you can also revert to an older
configuration. I haven't tried to do that since Eclipse 3.0, so I don't
know exactly how the steps are.
> So then I deleted my eclipse installation,
> downloaded eclipse 3.1.2, installed it, added the eclipseFP and darcs
> plugins. Now Windows -> Preferences -> Functional gives the error:
> Unable to create the selected preference page.
> Plug-in net.sf.eclipsefp.common.ui was unable to load class
> net.sf.eclipsefp.common.ui.preferences.FPPreferencesPage. The
> details just repeat the name of the class that cannot be loaded with
> no new information.
Well, this looks like a problem on our side, so I'll have to look into
it. Usually this kind of classloading problem has to do with plugin
activation. A plugin has roughly two parts, a declarative part that is
used by the platform to put the appropriate menu items and so on into
the UI, and a code part that is lazily loaded when the user wants to
actually execute that functionality. Now, if the plugin was correctly
installed, the UI shows the entry points, but if then something breaks
during plugin init, no code can be loaded, resulting in such
Could you perhaps have a look at the workspace log (the file .log in the
.metadata/ folder of your workspace location) if there is any additional
information (or perhaps just send us the entire log)?
Thanks && ciao,