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implement coercions involving instances properly

This commit is contained in:
Guido van Rossum 1995-01-10 15:24:06 +00:00
parent c206c766dd
commit 879c581826
1 changed files with 53 additions and 1 deletions
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54
Objects/classobject.c
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@ -924,6 +924,58 @@ halfbinop(v, w, opname, r_result, thisfunc, swapped)
return *r_result == NULL ? -1 : 0;
}
static int
instance_coerce(pv, pw)
object **pv;
object **pw;
{
object *v = *pv;
object *w = *pw;
object *coerce;
object *args;
object *coerced;
coerce = getattr(v, "__coerce__");
if (coerce == NULL) {
/* No __coerce__ method: always OK */
err_clear();
INCREF(v);
INCREF(w);
return 0;
}
/* Has __coerce__ method: call it */
args = mkvalue("(O)", w);
if (args == NULL) {
return -1;
}
coerced = call_object(coerce, args);
DECREF(args);
DECREF(coerce);
if (coerced == NULL) {
/* __coerce__ call raised an exception */
return -1;
}
if (coerced == None) {
/* __coerce__ says "I can't do it" */
DECREF(coerced);
return 1;
}
if (!is_tupleobject(coerced) || gettuplesize(coerced) != 2) {
/* __coerce__ return value is malformed */
DECREF(coerced);
err_setstr(TypeError,
"coercion should return None or 2-tuple");
return -1;
}
/* __coerce__ returned two new values */
*pv = gettupleitem(coerced, 0);
*pw = gettupleitem(coerced, 1);
INCREF(*pv);
INCREF(*pw);
DECREF(coerced);
return 0;
}
#define UNARY(funcname, methodname) \
static object *funcname(self) instanceobject *self; { \
@ -1018,7 +1070,7 @@ static number_methods instance_as_number = {
0, /*nb_and*/
0, /*nb_xor*/
0, /*nb_or*/
0, /*nb_coerce*/
(coercion)instance_coerce, /*nb_coerce*/
(unaryfunc)instance_int, /*nb_int*/
(unaryfunc)instance_long, /*nb_long*/
(unaryfunc)instance_float, /*nb_float*/