All examples on

https://docs.python.org/3/library/wsgiref.html

raise this exception:

Traceback (most recent call last):
  File "C:\Code\test\server.py", line 110, in <module>
    with make_server('', 8000, simple_app) as httpd:
AttributeError: __exit__

Tested with

Python 3.6.1 (v3.6.1:69c0db5, Mar 21 2017, 18:41:36) [MSC v.1900 64 bit (AMD64)] on win32

something is wrong in your setup then.  I suspect you have a mismatch between the python version you think you are running the one you are actually running, and/or which library code it is accessing.

Either that or you aren't really running the make_server from wsgiref.simple_server.

I tried a few online python 3 interpreters.

These give the same exception:

http://www.learnpython.org/en/Hello%2C_World%21
http://rextester.com/l/python3_online_compiler
http://ideone.com/pIMilt
http://www.tutorialspoint.com/execute_python3_online.php

And this one worked:

https://repl.it/languages/python3

the example i tried was:

from wsgiref.simple_server import make_server, demo_app
with make_server('', 8000, demo_app) as httpd:
    print("Serving HTTP on port 8000...")
    httpd.serve_forever()

My Python installation is a default x64 installation. No changes were made during installation, except installation path, which has no spaces in it. I have no third part modules installed which could interfer. I have also a Python 2.7 installed but it is not on my path.

I just found out that the example works in idle and if i do in a console:

python server.py

but not if i do just:

server.py

What is the secret behind this?

If you just type 'server.py' it will use whichever interpreter is associated with .py files, which might not be python3.  You may want to learn about the 'py' helper command.

What would that be? If i google 'py helper command' i get no good results.

It gets installed along with python3, I believe.  If you google for 'python py' you should see the pypi package version in the top hits.

I am not sure if the py package i found on PyPi is what you meant, but if you mean the py launcher (the py.exe in the windows dir), yes, i have that.

My system was indeed misconfigured as you correctly guessed, i had the .py filetype pointing to a Python version 3.5. I have now uninstalled everything, manually cleaned up the registry, reinstalled Python 3.6 and now everything works. Sorry, my mistake.

ok