Avoid creating META-INF/json/ directories for `.jar`-only directories

[dscho]

On Mon, 24 Mar 2014, Philippe CARL wrote:

Using Fiji, I have seen that when there is a plugin in .jar format in a
given folder there is (during the Fiji startup) quite often the creation
of a folder named "META-INF" inside which there is an empty folder named
"json" in the .jar folder.

Why are these folders created? Is there a way to get rid of these
folders creation?

[ctrueden]

Wouldn't it be better to simply not create that folder structure? I thought that was only supposed to happen when running from inside Eclipse, anyway? Or is it done for some other reason?

[dscho]

The problem is that we cannot detect whether we're running from inside Eclipse. So we use a tell-tale for that: if the first class path element is a bare folder, then we're running from Eclipse.

In this case, it breaks down, because the directory is added first (because of those pesky and fragile .class files allowed by ImageJ 1.x).

I guess it would not be a problem to add the directory last (or let the ij1-patcher sort it last) so that the EclipseHelper does not kick in. Even when compiling from within the Script Editor, it should work, because the Script Editor uses javac (which has no problems with annotation processors).

[dscho]

Oh, and the folder structure is used as a marker that the EclipseHelper ran...

[dscho]

But then, I guess we could really only write the directory structure iff there were .class files at all. Will go with that approach!

[ctrueden]

My vote would be to write the folder structure lazily: if the structure does not exist when it is time to write out the first annotation (e.g., org.scijava.plugin.Plugin), create it.

[dscho]

Addressed in 8e92558