Module imports, but doesn't have any attributes

Question

I am trying to import a Python module (fiasco). I cloned it from GitHub and everything appeared to be working fine. Importing it works, but when I try to type, for example iron = fiasco.Element('iron', [1e4, 1e6, 1e8]*u.K), I get the error module 'fiasco' has no attribute 'Element'. I am using Spyder's iPython console. This also fails if I start iPython from the terminal, but works if I start python3 from the terminal.

I had done this on two different computers - on one, it worked at first, but started giving me the same error after I restarted the kernel. On the other, it never worked at all.

If it helps: after importing, I tried typing fiasco. When I did this on the computer where it originally worked, the output was <module 'fiasco' from '/Users/shirman/fiasco/fiasco/__init__.py'>. Now, and on the computer it never worked on, it just says <module 'fiasco' (namespace)>. So maybe this has something to do with paths?

Addition: sys.path points to /Users/shirman, and several paths within /Users/shirman/anaconda3. The fiasco folder is in /Users/shirman.

Answer 1

You have inadvertently created a namespace package due to your sys.path setting. Namespace packages are directories without an __init__.py in the Python search path and allow loading of submodules or -packages from different paths (e.g. path1/foo/a.py and path2/foo/b.py can be imported as foo.a and foo.b).

The problem is that import fiasco finds /Users/shirman/fiasco first and imports it as a namespace package. If you set sys.path such that /Users/shirman/fiasco comes before /Users/shirman, the importer finds the actual package /Users/shirman/fiasco/fiasco first.

Namespace packages are a Python 3.3 feature, so either the other machine had a different sys.path setting, a really old Python 3 installation, or you were using Python 2.