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Implement isinstance(x, (A, B, ...)). Note that we only allow tuples,

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not other sequences (then we'd have to except strings, and we'd still
be susceptible to recursive attacks).
This commit is contained in:
Guido van Rossum 2001-10-07 20:54:12 +00:00
parent 1f733baa04
commit 03290ecbf1
2 changed files with 20 additions and 3 deletions
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17
Objects/abstract.c
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@ -1805,6 +1805,20 @@ PyObject_IsInstance(PyObject *inst, PyObject *cls)
else if (PyType_Check(cls)) { else if (PyType_Check(cls)) {
retval = PyObject_TypeCheck(inst, (PyTypeObject *)cls); retval = PyObject_TypeCheck(inst, (PyTypeObject *)cls);
} }
else if (PyTuple_Check(cls)) {
/* Not a general sequence -- that opens up the road to
recursion and stack overflow. */
int i, n;
n = PyTuple_GET_SIZE(cls);
for (i = 0; i < n; i++) {
retval = PyObject_IsInstance(
inst, PyTuple_GET_ITEM(cls, i));
if (retval != 0)
break;
}
return retval;
}
else if (!PyInstance_Check(inst)) { else if (!PyInstance_Check(inst)) {
if (__class__ == NULL) { if (__class__ == NULL) {
__class__ = PyString_FromString("__class__"); __class__ = PyString_FromString("__class__");
@ -1827,7 +1841,8 @@ PyObject_IsInstance(PyObject *inst, PyObject *cls)
if (retval < 0) { if (retval < 0) {
PyErr_SetString(PyExc_TypeError, PyErr_SetString(PyExc_TypeError,
"isinstance() arg 2 must be a class or type"); "isinstance() arg 2 must be a class or type "
"or tuple of those");
} }
return retval; return retval;
} }

6
Python/bltinmodule.c
View file

@ -1641,10 +1641,12 @@ builtin_isinstance(PyObject *self, PyObject *args)
} }
static char isinstance_doc[] = static char isinstance_doc[] =
"isinstance(object, class-or-type) -> Boolean\n\ "isinstance(object, class-or-type-or-tuple) -> Boolean\n\
\n\ \n\
Return whether an object is an instance of a class or of a subclass thereof.\n\ Return whether an object is an instance of a class or of a subclass thereof.\n\
With a type as second argument, return whether that is the object's type."; With a type as second argument, return whether that is the object's type.\n\
The form using a tuple, isinstance(x, (A, B, ...)), is a shortcut for\n\
isinstance(x, A) or isinstance(x, B) or ... (etc.).";
static PyObject * static PyObject *