[zeromq-dev] Python bindings strings and bytes

Arnaud Loonstra arnaud at sphaero.org
Wed Nov 11 12:43:06 CET 2015

This is a frequent issue dealing with Python but how do we want to deal 
with strings? Python strings are a bit cumbersome when dealing with C.

For example to use the Zyre bindings in python one needs to do one of 
the following:

> from zyre import Zyre
> zn = Zyre(b'MyZyreNode')


> zn = Zyre('MyZyreNode'.encode('utf-8'))

This will work in both major Python versions.
The current unittest uses:

> z1 = Zyre('t1')

which only works in Python 2.

In Python 3 this excepts:

Traceback (most recent call last):
   File "test.py", line 6, in test_all
     z1 = Zyre('t1')
   File "/home/people/arnaud/src/zyre/bindings/python/zyre.py", line 
129, in __init__
     self._as_parameter_ = lib.zyre_new(args[0]) # Creation of new raw 
ctypes.ArgumentError: argument 1: <class 'TypeError'>: wrong type

We could just use bytes for everything but it has some consequences and 
makes it a bit un-pythonic. For example the Zyre unittest tests for the 
type of a Zyre event:

> self.assertEquals(e.type(), 'join')

type() returns a Python string and not a bytes object.

Actually I don't know of any other way as converting to a python string 
needs encoding. Anybody thoughts about this?



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