[Python-Dev] Py_SIZE vs PyXXX_GET_SIZE

[Victor Stinner]

We may modify PyXXX_GET_SIZE() to add assert(PyXXX_Check()) to help to
detect bugs and misuses of these macros in debug mode.

The problem is that I expect a compilation error on PyXXX_GET_SIZE()=size.

The new PyDict_GET_SIZE() macro has the assertion. Use Py_SIZE() to set the
size.

Victor

Le 20 mars 2017 12:28, "Serhiy Storchaka" <storchaka at gmail.com> a écrit :

> What is the preferable way of getting the size of tuple, list, bytes,
> bytearray: Py_SIZE or PyTuple_GET_SIZE, PyList_GET_SIZE, PyBytes_GET_SIZE,
> PyByteArray_GET_SIZE? Are macros for concrete types more preferable or they
> are outdated?
>
> On one hand concrete type macros are longer than Py_SIZE, and since
> concrete type macros are defined not for all PyVarObject types we need to
> use Py_SIZE for them in any case (for example for PyLongObject and
> PyTypeObject).
>
> On other hand we can add asserts for checking that concrete type macros
> are used with correct types. When I wrote a patch that replaces Py_SIZE
> with concrete type macros I found two cases of misusing Py_SIZE with dict
> object: one in _json.c (already fixed in 3023ebb43f7607584c3e123aff56e867cb04a418)
> and other in dictobject.c (still not fixed). If prefer using concrete type
> macros this would unlikely happen.
>
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