[Python-Dev] Convert Py_Buffer to Py_UNICODE (original) (raw)

M.-A. Lemburg mal at egenix.com
Mon May 2 21:12:27 CEST 2011

Sijin Joseph wrote:

Hi - I am working on a patch where I have an argument that can either be a unicode string or binary data, I parse the argument using the PyArgParseTuple method using the s* format specification and get a PyBuffer.

I now need to convert this PyBuffer object to a PyUnicode and pass it into a function. What is the best way to do this? If I determine that the passed argument was binary using another flag parameter then I am passing PyBuffer->buf as a pointer to the start of the data.

I don't understand why you'd want to convert PyUnicode to PyBytes (encoded as UTF-8), only to decode it again afterwards in order to pass it to some other PyUnicode API.

It'd be more efficient to use the "O" parser marker and then use PyObject_GetBuffer() to convert non-PyUnicode objects to a Py_buffer.

This is in winsound module, here's the relevant code snippet

soundplaysound(PyObject *s, PyObject *args) { Pybuffer *buffer; int flags; int ok; LPCWSTR pszSound; if (PyArgParseTuple(args, "s*i:PlaySound", &buffer, &flags)) { if (flags & SNDASYNC && flags & SNDMEMORY) { /* Sidestep reference counting headache; unfortunately this also prevent SNDLOOP from memory. */ PyBufferRelease(buffer); PyErrSetString(PyExcRuntimeError, "Cannot play asynchronously from memory"); return NULL; } if(flags & SNDMEMORY) { pszSound = buffer->buf; } else { /* pszSound = ????; */ } -- Sijin

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