[issue29548] deprecate PyEval_Call*() functions.
INADA Naoki
report at bugs.python.org
Mon Feb 13 22:00:32 EST 2017
INADA Naoki added the comment:
Thanks, Lemburg to pointing it out.
Here is detail of the difference.
## PyEval_CallFunction(), PyEval_CallMethod()
They are very similar to PyObject_CallFunction() and PyObject_CallMethod(). difference are:
* PyEval_Call...() doesn't respect Py_SSIZE_T_CLEAN
* PyObject_Call... has following special case. PyEval_CallFunction(callable, "i", (int)i) will raise TypeError("keyword list must be a tuple") and PyObject_CallFunction(callable, "i", (int)i) calls `callable(i)`
if (nargs == 1 && PyTuple_Check(stack[0])) {
/* Special cases for backward compatibility:
- PyObject_CallFunction(func, "O", tuple) calls func(*tuple)
- PyObject_CallFunction(func, "(OOO)", arg1, arg2, arg3) calls
func(*(arg1, arg2, arg3)): func(arg1, arg2, arg3) */
PyObject *args = stack[0];
result = _PyObject_FastCall(callable,
&PyTuple_GET_ITEM(args, 0),
PyTuple_GET_SIZE(args));
}
PyEval_CallFunction is not called from Python source tree.
PyEval_CallMethod has only one caller in tree and format string is "(Oi)". It can be replaced with PyObject_CallMethod safely.
## PyEval_CallObject(), PyEval_CallObjectWithKeywords()
PyEval_CallObject() is a just macro calling PyEval_CallObjectWithKeywords() (call it COWK later).
PyEval_CallObject() is identical to PyObject_CallObject(). Only difference is it's a macro or function.
COWK is similar to PyObject_Call(), but COWK raise TypeError when args is not a tuple or kwds is not a dictionary and PyObject_Call() uses assert.
There are only two caller of PyEval_CallObjectWithKeywords() other than PyEval_CallObject and PyObject_CallObject.
One is tp_call of weakcallableproxy. Type of kwargs is checked before calling tp_call.
Another is in threading (boot->keyw). The threading module checks it's a dict.
So replacing them to PyObject_CallObject() is safe.
----
While they are complex API, there are few (or no) callers in Python tree.
It's too hard to maintain. Actually, I found regression of COWK in Python 3.6.
https://github.com/python/cpython/commit/155ea65e5c88d250a752ee5321860ef11ede4085
It calls _PyObject_FastCallDict() when args is NULL. If kwargs is not dict, it can crash instead of raising TypeError.
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<http://bugs.python.org/issue29548>
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