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From: Ian Kelly <ian.g.kelly@gmail.com>
Date: Mon, 20 Oct 2014 17:48:23 -0600
Subject: Re: Simple import in python 3 errors with complaint about bytes
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On Mon, Oct 20, 2014 at 5:29 PM, Mike Boyle <moboyle79@outlook.com> wrote:
> I'm modifying an extension written with the c-api to have a datatype of q=
uaternions <https://github.com/moble/numpy_quaternion>, with one of the goa=
ls being python 3 support.  It works nicely in python 2.7, but for python 3=
.x gives an error that I can't find anywhere on the google.  The directory =
looks like this:
>
> .../site-packages/
>     quaternion/
>         __init__.py
>         numpy_quaternion.so
>
> __init__.py contains a line like this:
>
>     from .numpy_quaternion import quaternion
>
> But when it hits that line, python 3 throws its hands up in disgust:
>
>> python -c 'import quaternion'
> Traceback (most recent call last):
>   File "<string>", line 1, in <module>
>   File "/Users/mynamehere/.continuum/anaconda/envs/py3k/lib/python3.4/sit=
e-packages/quaternion/__init__.py", line 3, in <module>
>     from .numpy_quaternion import quaternion
> TypeError: __import__() argument 1 must be str, not bytes
>
> The only thing before that line is `import numpy as np`, which typically =
works just fine.  Obviously, I'm using python3.4 to compile and (attempt to=
) import (with a conda environment), so it's not something as dumb as using=
 the wrong python.  Also, this is the result for both me on my laptop and T=
ravis-CI <https://travis-ci.org/moble/numpy_quaternion>, so it doesn't seem=
 to be anything peculiar to my installation.  I've posted this question on =
stackoverflow, but haven't gotten much interest; the only responder suggest=
ed I ask here instead.
>
> Any ideas what's going wrong, or where I can go from here?

I question whether the error is really coming from that particular
import line.  Try shadowing the __import__ function to see what's
actually being passed there.  E.g.:

>>> orig_import =3D __import__
>>> def debug_import(name, globals=3DNone, locals=3DNone, fromlist=3D(), le=
vel=3D0):
...   print("debug_import:", name, globals, locals, fromlist, level)
...   return orig_import(name, globals, locals, fromlist, level)
...
>>> import builtins
>>> builtins.__import__ =3D debug_import
>>> import sys
debug_import: sys {'__spec__': None, '__loader__': <class
'_frozen_importlib.BuiltinImporter'>, '__package__': None, 'builtins':
<module 'builtins' (built-in)>, 'orig_import': <built-in function
__import__>, '__builtins__': <module 'builtins' (built-in)>,
'__name__': '__main__', '__doc__': None, 'debug_import': <function
debug_import at 0x7f6096aac9d8>} {'__spec__': None, '__loader__':
<class '_frozen_importlib.BuiltinImporter'>, '__package__': None,
'builtins': <module 'builtins' (built-in)>, 'orig_import': <built-in
function __import__>, '__builtins__': <module 'builtins' (built-in)>,
'__name__': '__main__', '__doc__': None, 'debug_import': <function
debug_import at 0x7f6096aac9d8>} None 0