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* Objects/classobject.c, Include/classobject.h: added __getattr__ 

and __setattr__ support to override getattr(x, name) and
	setattr(x, name, value) for class instances.  This uses a special
	hack whereby the class is supposed to be static: the __getattr__
	and __setattr__ methods are looked up only once and saved in the
	instance structure for speed
This commit is contained in:
Guido van Rossum 1994-08-12 12:49:46 +00:00
parent e025e31de6
commit e149fa2a1e
2 changed files with 111 additions and 17 deletions
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12
Include/classobject.h
View File

@ -30,6 +30,12 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
/* Class object interface */
#ifdef WITH_THREAD
#include "thread.h"
#else
#define get_thread_ident() 1L
#endif
/* Revealing some structures (not for general use) */
typedef struct {
@ -43,6 +49,12 @@ typedef struct {
OB_HEAD
classobject *in_class; /* The class object */
object *in_dict; /* A dictionary */
object *in_getattr; /* A method or NULL */
object *in_setattr; /* A method or NULL */
long in_ident; /* A thread ident or 0 */
#ifdef WITH_THREAD
type_lock *in_lock; /* A lock or NULL */
#endif
} instanceobject;
extern typeobject Classtype, Instancetype, Instancemethodtype;

116
Objects/classobject.c
View File

@ -104,21 +104,23 @@ class_getattr(op, name)
{
register object *v;
classobject *class;
if (strcmp(name, "__dict__") == 0) {
INCREF(op->cl_dict);
return op->cl_dict;
}
if (strcmp(name, "__bases__") == 0) {
INCREF(op->cl_bases);
return op->cl_bases;
}
if (strcmp(name, "__name__") == 0) {
if (op->cl_name == NULL)
v = None;
else
v = op->cl_name;
INCREF(v);
return v;
if (name[0] == '_' && name[1] == '_') {
if (strcmp(name, "__dict__") == 0) {
INCREF(op->cl_dict);
return op->cl_dict;
}
if (strcmp(name, "__bases__") == 0) {
INCREF(op->cl_bases);
return op->cl_bases;
}
if (strcmp(name, "__name__") == 0) {
if (op->cl_name == NULL)
v = None;
else
v = op->cl_name;
INCREF(v);
return v;
}
}
v = class_lookup(op, name, &class);
if (v == NULL) {
@ -280,11 +282,25 @@ newinstanceobject(class, arg)
INCREF(class);
inst->in_class = (classobject *)class;
inst->in_dict = newdictobject();
inst->in_getattr = NULL;
inst->in_setattr = NULL;
#ifdef WITH_THREAD
inst->in_lock = NULL;
inst->in_ident = 0;
#endif
if (inst->in_dict == NULL ||
addaccess((classobject *)class, inst) != 0) {
DECREF(inst);
return NULL;
}
inst->in_setattr = instance_getattr(inst, "__setattr__");
err_clear();
inst->in_getattr = instance_getattr(inst, "__getattr__");
err_clear();
#ifdef WITH_THREAD
if (inst->in_getattr != NULL)
inst->in_lock = allocate_lock();
#endif
init = instance_getattr(inst, "__init__");
if (init == NULL) {
err_clear();
@ -345,6 +361,12 @@ instance_dealloc(inst)
return; /* __del__ added a reference; don't delete now */
DECREF(inst->in_class);
XDECREF(inst->in_dict);
XDECREF(inst->in_getattr);
XDECREF(inst->in_setattr);
#ifdef WITH_THREAD
if (inst->in_lock != NULL)
free_lock(inst->in_lock);
#endif
free((ANY *)inst);
}
@ -370,6 +392,32 @@ instance_getattr(inst, name)
if (v == NULL) {
v = class_lookup(inst->in_class, name, &class);
if (v == NULL) {
object *func;
long ident;
if ((func = inst->in_getattr) != NULL &&
inst->in_ident != (ident = get_thread_ident())) {
object *args;
#ifdef WITH_THREAD
type_lock lock = inst->in_lock;
if (lock != NULL) {
BGN_SAVE
acquire_lock(lock, 0);
END_SAVE
}
#endif
inst->in_ident = ident;
args = mkvalue("(s)", name);
if (args != NULL) {
v = call_object(func, args);
DECREF(args);
}
inst->in_ident = 0;
#ifdef WITH_THREAD
if (lock != NULL)
release_lock(lock);
#endif
return v;
}
err_setstr(AttributeError, name);
return NULL;
}
@ -410,6 +458,18 @@ instance_setattr(inst, name, v)
object *v;
{
object *ac;
if (inst->in_setattr != NULL) {
object *args = mkvalue("(sO)", name, v);
if (args != NULL) {
object *res = call_object(inst->in_setattr, args);
DECREF(args);
if (res != NULL) {
DECREF(res);
return 0;
}
}
return -1;
}
if (name[0] == '_' && name[1] == '_') {
int n = strlen(name);
if (name[n-1] == '_' && name[n-2] == '_') {
@ -824,11 +884,33 @@ BINARY(instance_mul, "__mul__")
BINARY(instance_div, "__div__")
BINARY(instance_mod, "__mod__")
BINARY(instance_divmod, "__divmod__")
BINARY(instance_pow, "__pow__")
UNARY(instance_neg, "__neg__")
UNARY(instance_pos, "__pos__")
UNARY(instance_abs, "__abs__")
static object *
instance_pow(self, other, modulus)
instanceobject *self;
object *other, *modulus;
{
object *func, *arg, *res;
if ((func = instance_getattr(self, "__pow__")) == NULL)
return NULL;
if (modulus == None)
arg = mkvalue("O", other);
else
arg = mkvalue("(OO)", other, modulus);
if (arg == NULL) {
DECREF(func);
return NULL;
}
res = call_object(func, arg);
DECREF(func);
DECREF(arg);
return res;
}
static int
instance_nonzero(self)
instanceobject *self;
@ -922,7 +1004,7 @@ static number_methods instance_as_number = {
(binaryfunc)instance_div, /*nb_divide*/
(binaryfunc)instance_mod, /*nb_remainder*/
(binaryfunc)instance_divmod, /*nb_divmod*/
(binaryfunc)instance_pow, /*nb_power*/
(ternaryfunc)instance_pow, /*nb_power*/
(unaryfunc)instance_neg, /*nb_negative*/
(unaryfunc)instance_pos, /*nb_positive*/
(unaryfunc)instance_abs, /*nb_absolute*/