[zeromq-dev] Python bindings strings and bytes

[Arnaud Loonstra]

 From the binding perspective this would be easiest. From a user 
perspective it isn't. However if we need to please the user, automatic 
generation of bindings gets very difficult I guess.

Could we embrace Python's Buffer Protocol?
https://docs.python.org/3/c-api/buffer.html
Also makes the exposed bytes mutable?

We could generate less cryptic exceptions indeed.

Rg,

Arnaud

On 2015-11-11 17:42, Michel Pelletier wrote:
> My personal opinion is that the API should use bytes, and only bytes,
> and never return or accept any unicode objects.
>
> Its a bit brutal but then at least the rules are simple.  Pass
> unicode, get a clear exception.
>
> On Wed, Nov 11, 2015 at 3:43 AM, Arnaud Loonstra <arnaud at sphaero.org
> [3]> wrote:
>
>> 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(bMyZyreNode)
>>
>> or
>>
>> > 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
>> type
>> 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 dont know of any other way as converting to a python
>> string
>> needs encoding. Anybody thoughts about this?
>>
>> Rg,
>>
>> Arnaud
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>
>
>
> Links:
> ------
> [1] mailto:zeromq-dev at lists.zeromq.org
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