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

Haoyu Bai divinekid at gmail.com
Sun Aug 2 07:45:11 CEST 2009

On Tue, Jul 28, 2009 at 10:11 PM, Robert Smallshire<Robert.Smallshire at roxar.com> wrote:

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 wchart > 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 wchart* 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 PyUnicodeType rather than PyStringType. 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? Cheers, Robert Smallshire DISCLAIMER: This message contains information that may be privileged or confidential and is the property of the Roxar Group. It is intended only for the person to whom it is addressed. If you are not the intended recipient, you are not authorised to read, print, retain, copy, disseminate, distribute, or use this message or any part thereof. If you receive this message in error, please notify the sender immediately and delete all copies of this message.

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Hi,

Sorry for the delayed reply because I was busy on some other stuff last week.

Currently the unicode support I implemented for Python 3 contains some converters for PyUnicode and C++ string types, and a boost::python::str class that conditionally call PyUnicode API in Python 3 or PyString API in Python 2. So a boost::python::unicode type would be very useful for Python 2. And for Python 3, we might need to rename the new "unicode" class to "str", and the old "str" class to "bytes", in order to reflect the change of Python.

I'd happy to help to integrate and test it if send your code to the boost trac.

Thank you!

-- Haoyu Bai School of Computing, National University of Singapore.

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