how come an Eclipse plugin that targets Eclipse version 3.5 works with Juno but not Indigo or Kepler?

Question

I developed an Eclipse plugin using Juno (version 4.2) and specified in the plugin.xml file that it is supposed to target Eclipse version 3.5.

However, when I copy the jar file to the "dropins" folder of Eclipse Indigo (previous version) or Eclipse Kepler (current version), it is listed as an installed plugin, but doesn't load on startup.

Could it be that the particular instances of Kepler/Indigo that I tried the plugin on are missing at least one of the plugin's dependencies?

Answer 1

The <?eclipse version="3.5"?> tag in plugin.xml file does not specifies what version of Eclipse you want to target. It just specifies the version of plugin.xml syntax that you wish to use. Newer versions of Eclipse will support old syntax, but not the other way around.

What really controls the version of Eclipse that your plugin supports are the dependencies specified in plugin MANIFEST.MF files and feature dependencies in feature.xml files. A common problem is being unable to meet the version constraint specified in one of those dependencies.

The trouble with using dropins folder installation method is that you don't see the problem that documents why your plugin could not be activated. Instead, use the "install additional software" wizard in Eclipse and you will see the issue when it refuses to install into one of your target configurations.