Issue1896

This is required by the compileall module, which I need to make binary jars so I can test my ERP client on 2.7.

Renamed the issue.

I also committed the missing imp.get_magic() function, but I think I was too hasty. For one, the value should be unique to Jython. Second, there may be a good reason why the function is missing from Jython 2.5. It's highly likely that my commit needs to be reverted. However, I have no clue how to fix the compileall module then.

On further investigation I discovered that in 2.7, the compileall module reads the first 8 bytes of an existing target file and checks the magic number and the modification time. Python 2.5 does not do this. I don't know enough about class files to know if or how this applies to Jython.

compileall works when run like this within the jython27a2 REPL:
import compileall
compileall.compile_dir("src", force=1)

but it fails when run as a subprocess:
subprocess.call(['java', '-jar', jython_jar, '-m', 'compileall', src])

The reason is of course the force=1, it prevents compileall from trying to read in the magic number.
Therefore, -f will work, too:

subprocess.call(['java', '-jar', jython_jar, '-m', 'compileall', '-f', tmpdir])

Works fine now, in the ways I would assume compileall is actually used - by setuptools, pip, etc, etc - basically all the stuff we have been working on for a while. Or jython27 -m compileall

I assume this bug has just been sitting here unnoticed until now, certainly by me. Please respond if this is not the case.