python adding variables to imported modules

Question

I wasn't looking what I had previously written on the line so I accidently declared a variable in ipython as:

np.zerosn=10

Surprisingly this was allowed. So I thought that maybe it was because you can name use periods in your variable names, but that is not the case. So I'm wondering what is actually happening. Is this adding a new variable to the numpy module?

Answer 1

Yes.

In general, (most/many) python objects have dynamic attribute spaces, and you can stick whatever you want onto them whenever you want. And modules are just objects. Their attribute space is essentially the same as their global scope.

Pure python functions are another (perhaps surprising) example of something onto which you can stick arbitrary attributes, though these are not associated with the function's local scope.

Most 'builtin' types (ie those which are implemented in extension modules, rather than those that are found in the __builtins__ module) and their instances, do not have dynamic attribute spaces. Neither do pure python types with __slots__ .