[zeromq-dev] Python bindings strings and bytes

[Michel Pelletier]

On Wed, Nov 11, 2015 at 12:29 PM, Arnaud Loonstra <arnaud at sphaero.org>
wrote:

>  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.
>
>
To be fair I don't have a lot of skin in the game so take my opinion with
sufficient salt, the nice thing about bytes is that it's dirt simple.


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

Using buffer would be great, both bytes and bytearray implement it.  I
think it can be used with mmap objects as well. +1

-Michel


>
> 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
> >> _______________________________________________
> >> zeromq-dev mailing list
> >> zeromq-dev at lists.zeromq.org [1]
> >> http://lists.zeromq.org/mailman/listinfo/zeromq-dev [2]
> >
> >
> >
> > Links:
> > ------
> > [1] mailto:zeromq-dev at lists.zeromq.org
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> > [3] mailto:arnaud at sphaero.org
>
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