What to do when an Eclipse plug-in doesn’t work

Yesterday I spent an hour trying to help dj

Padák get a plug-in working in Eclipse. We didn’t manage it in the

end, unfortunately, but I’d like to share a few general tips that have always

worked for me. I’d welcome your observations too.

What to know before installing

Versions, or birds of a feather

The basic rule is to install only plug-ins made for the version of Eclipse
you use. Eclipse follows x.y.z versioning. The x is the major
version. Major versions differ in the Eclipse API, which the
plug-ins depend heavily on. The y is the minor version. I’m not quite
sure, but the API may change there too, probably only in

backward-compatible ways, such as adding to the API. An increase in z

means
maintenance changes such as bug fixes.

The current release is 3.1 M4, where M means milestone. As a rule,

the API keeps changing throughout
the milestones. Eclipse 3.0 had nine

milestones during development, and the API only started to look frozen around M7. A

later milestone didn’t necessarily mean a better one. Either
M8 or M9 was noticeably slower. If you run a milestone build

of Eclipse, nobody can guarantee that a plug-in will work.

Where to install a plug-in

There are two ways to install a plug-in. The first is
Install/Update (Help >> Software Updates >> Find and Install), but that works
only for some kinds of plug-in. If it’s an option, the
plug-in site will have instructions. Use it and you’ll at least
save time looking for dependencies or other components the plug-in
needs.

The other way assumes you’ve downloaded the plug-in or got it from somewhere

else. Some plug-ins come in a directory structure you can simply

copy into ECLIPSE_HOME, the eclipse directory. You’ll recognize the structure

by a
plugins directory or by both plugins and features. If the package contains only
the plug-in directory itself, copy it to ECLIPSE_HOME\plugins. After installing a

plug-in,
it’s a good idea to restart the IDE.

Where the plug-in shows up

Often a user doesn’t know or hasn’t read which part of

Eclipse the plug-in integrates with. It may appear as a view, perspective
or wizard. If it has settings, look under Window >>
Preferences. A tip for diehards who still can’t find where the blasted
plug-in ended up. Examine its plugin.xml to see the extension points
it’s attached to. I’m not entirely serious about that last tip.

How to tell whether the plug-in is failing

After installing a plug-in and restarting the IDE, everything may look right but the plug-in
won’t work. First check whether it installed
without errors. There are several ways to check.

• Help >> About >> Plugin Details (the plug-in should be listed)
• Help >> Software Updates >> Manage Configuration (the plug-in should
  be listed)
• Window >> Show view >> other >> PDE >> Plug-ins (the plug-in should
  be listed)

If the plug-in is absent, reports an error or behaves incorrectly,
check the Error log. Eclipse has an Error log view you can open
through Window >> Show view >> Other >> PDE Runtime. If Eclipse won’t
start at all, you’ll have to read the log from the file

ECLIPSE_HOME\workspace\.metadata\.log. If the messages don’t help,
it’s time to call a friend, Google.

Plug-in dependencies are a major trap. I’ve had modeling
tools that depended on GEF. Without the right version of GEF,
the plug-in didn’t work. The log and Google can help you find out. If the plug-in

should work with your version of Eclipse and still doesn’t, try installing

it in a clean environment. Install a fresh copy of Eclipse and

add only the plug-in you want and any dependencies.