[C++-sig] boost::python::str and Python's str and unicode types

Ralf W. Grosse-Kunstleve rwgk at yahoo.com
Tue Jul 28 19:26:02 CEST 2009

I'd be happy to help out, but I don't know if/how this could interfere with Haoyu Bai's work.
Could you post your patches to the trac system at svn.boost.org so we can have a look
and figure out a way forward?

----- Original Message ----
From: Robert Smallshire <Robert.Smallshire at roxar.com>
To: Development of Python/C++ integration <cplusplus-sig at python.org>
Sent: Tuesday, July 28, 2009 7:11:35 AM
Subject: Re: [C++-sig] boost::python::str and Python's str and unicode types

> On 07/23/2009 10:17 AM, Robert Smallshire wrote:
> > Hello,
> >
> > I'm looking for some confirmation that my understanding of what
> > boost.python is doing is correct.
> >
> > > From what I understand boost::python::str represents the str
> > (PyStringObject) type in Python.  Unless I'm missing
> something, here
> > doesn't seem to be anything like boost::python::unicode
> representing
> > the unicode type (PyUnicodeObject).
> >
> > Boost.Python does have a built-in conversion from std::wstring to
> > object, but this creates a str in Python, so presumably
> there is some
> > (lossy?) decoding going on here.
> >
> > It seems that to directly create a PyUnicodeObject from C++ I will
> > need to do one or more of the following:
> >
> > 1) Directly use the Python C API to create and manipulate
> > PyUnicodeObject.
> > 2) Create my own subclass of boost::python::object called
> for example
> > 'unicode', which would be similar to the str class provided
> out of the
> > box, but would use PyUnicodeObject underneath and deal with wchar_t
> > rather than char.

I have modified my local build of boost.python to include a
boost::python::unicode class, together with appropriate conversions from
wchar, const wchar_t* and std::wstring, together with additional tests
in the boost.python test suite.  As you would expect, the code is
closely derived from the existing boost::python::str code but uses the
Python C API for PyUnicode_Type rather than PyString_Type. There are no
breaking changes to the existing boost.python API.

I'd like to contribute these changes back to boost.python so they can be
hopefully integrated into future official Boost releases.  What is the
procedure for this?  Where do I start?


Robert Smallshire

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