Import from a package with known import failure

Question

What I want to achieve is as follows:

I have a python package, let's call it foo, comprising a directory foo containing an __init__.py and, under normal use a compiled extension library (either a .so or a .pyd file), which __init__.py imports into the top level namespace.

Now, the problem is that I wish the top level namespace to contain a version string which is available to setup.py during building and packaging, when the extension library is not necessarily available (not yet built), and so would cause an ImportError when trying to import foo.version.

Now, clearly, I could have an exception handler in __init__.py that just ignores failures in importing anything, but this is not ideal as there may be a real reason that the user cares about why the package can't be imported.

Is there some way I can have the version string in a single place in the package, have it importable, yet not break the exceptions from attempts to import the extension?

Answer 1

As opposed to ignoring failures when importing print out a trace message or a warning so that the user will still get the negative feedback.

As for importing a specific subfile if you are using python 3.3+ (or python 2.7) you can use imp.load_source which accepts a pathname of a file you want to import.