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Diffstat (limited to 'Doc/c-api/arg.rst')
| -rw-r--r-- | Doc/c-api/arg.rst | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/Doc/c-api/arg.rst b/Doc/c-api/arg.rst index 94f62f1..e4b91b9 100644 --- a/Doc/c-api/arg.rst +++ b/Doc/c-api/arg.rst @@ -42,12 +42,18 @@ variable(s) whose address should be passed. responsible** for calling ``PyBuffer_Release`` with the structure after it has processed the data. -``s#`` (string, Unicode or any read buffer compatible object) [const char \*, int] +``s#`` (string, Unicode or any read buffer compatible object) [const char \*, int or :ctype:`Py_ssize_t`] This variant on ``s*`` stores into two C variables, the first one a pointer to a character string, the second one its length. All other read-buffer compatible objects pass back a reference to the raw internal data representation. Since this format doesn't allow writable buffer compatible - objects like byte arrays, ``s*`` is to be preferred. + objects like byte arrays, ``s*`` is to be preferred. The type of + the length argument (int or :ctype:`Py_ssize_t`) is controlled by + defining the macro :cmacro:`PY_SSIZE_T_CLEAN` before including + :file:`Python.h`. If the macro was defined, length is a :ctype:`Py_ssize_t` + rather than an int. This behavior will change in a future Python + version to only support :ctype:`Py_ssize_t` and drop int support. + It is best to always define :cmacro:`PY_SSIZE_T_CLEAN`. ``y`` (bytes object) [const char \*] This variant on ``s`` converts a Python bytes or bytearray object to a C |