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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
parent
e025e31de6
commit
e149fa2a1e
@ -30,6 +30,12 @@ OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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/* Class object interface */
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#ifdef WITH_THREAD
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#include "thread.h"
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#else
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#define get_thread_ident() 1L
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#endif
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/* Revealing some structures (not for general use) */
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typedef struct {
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@ -43,6 +49,12 @@ typedef struct {
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OB_HEAD
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classobject *in_class; /* The class object */
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object *in_dict; /* A dictionary */
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object *in_getattr; /* A method or NULL */
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object *in_setattr; /* A method or NULL */
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long in_ident; /* A thread ident or 0 */
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#ifdef WITH_THREAD
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type_lock *in_lock; /* A lock or NULL */
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#endif
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} instanceobject;
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extern typeobject Classtype, Instancetype, Instancemethodtype;
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@ -104,21 +104,23 @@ class_getattr(op, name)
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{
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register object *v;
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classobject *class;
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if (strcmp(name, "__dict__") == 0) {
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INCREF(op->cl_dict);
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return op->cl_dict;
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}
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if (strcmp(name, "__bases__") == 0) {
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INCREF(op->cl_bases);
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return op->cl_bases;
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}
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if (strcmp(name, "__name__") == 0) {
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if (op->cl_name == NULL)
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v = None;
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else
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v = op->cl_name;
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INCREF(v);
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return v;
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if (name[0] == '_' && name[1] == '_') {
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if (strcmp(name, "__dict__") == 0) {
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INCREF(op->cl_dict);
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return op->cl_dict;
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}
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if (strcmp(name, "__bases__") == 0) {
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INCREF(op->cl_bases);
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return op->cl_bases;
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}
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if (strcmp(name, "__name__") == 0) {
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if (op->cl_name == NULL)
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v = None;
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else
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v = op->cl_name;
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INCREF(v);
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return v;
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}
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}
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v = class_lookup(op, name, &class);
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if (v == NULL) {
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@ -280,11 +282,25 @@ newinstanceobject(class, arg)
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INCREF(class);
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inst->in_class = (classobject *)class;
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inst->in_dict = newdictobject();
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inst->in_getattr = NULL;
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inst->in_setattr = NULL;
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#ifdef WITH_THREAD
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inst->in_lock = NULL;
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inst->in_ident = 0;
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#endif
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if (inst->in_dict == NULL ||
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addaccess((classobject *)class, inst) != 0) {
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DECREF(inst);
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return NULL;
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}
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inst->in_setattr = instance_getattr(inst, "__setattr__");
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err_clear();
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inst->in_getattr = instance_getattr(inst, "__getattr__");
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err_clear();
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#ifdef WITH_THREAD
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if (inst->in_getattr != NULL)
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inst->in_lock = allocate_lock();
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#endif
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init = instance_getattr(inst, "__init__");
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if (init == NULL) {
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err_clear();
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@ -345,6 +361,12 @@ instance_dealloc(inst)
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return; /* __del__ added a reference; don't delete now */
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DECREF(inst->in_class);
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XDECREF(inst->in_dict);
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XDECREF(inst->in_getattr);
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XDECREF(inst->in_setattr);
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#ifdef WITH_THREAD
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if (inst->in_lock != NULL)
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free_lock(inst->in_lock);
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#endif
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free((ANY *)inst);
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}
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@ -370,6 +392,32 @@ instance_getattr(inst, name)
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if (v == NULL) {
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v = class_lookup(inst->in_class, name, &class);
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if (v == NULL) {
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object *func;
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long ident;
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if ((func = inst->in_getattr) != NULL &&
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inst->in_ident != (ident = get_thread_ident())) {
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object *args;
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#ifdef WITH_THREAD
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type_lock lock = inst->in_lock;
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if (lock != NULL) {
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BGN_SAVE
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acquire_lock(lock, 0);
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END_SAVE
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}
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#endif
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inst->in_ident = ident;
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args = mkvalue("(s)", name);
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if (args != NULL) {
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v = call_object(func, args);
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DECREF(args);
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}
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inst->in_ident = 0;
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#ifdef WITH_THREAD
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if (lock != NULL)
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release_lock(lock);
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#endif
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return v;
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}
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err_setstr(AttributeError, name);
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return NULL;
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}
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@ -410,6 +458,18 @@ instance_setattr(inst, name, v)
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object *v;
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{
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object *ac;
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if (inst->in_setattr != NULL) {
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object *args = mkvalue("(sO)", name, v);
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if (args != NULL) {
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object *res = call_object(inst->in_setattr, args);
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DECREF(args);
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if (res != NULL) {
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DECREF(res);
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return 0;
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}
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}
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return -1;
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}
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if (name[0] == '_' && name[1] == '_') {
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int n = strlen(name);
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if (name[n-1] == '_' && name[n-2] == '_') {
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@ -824,11 +884,33 @@ BINARY(instance_mul, "__mul__")
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BINARY(instance_div, "__div__")
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BINARY(instance_mod, "__mod__")
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BINARY(instance_divmod, "__divmod__")
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BINARY(instance_pow, "__pow__")
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UNARY(instance_neg, "__neg__")
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UNARY(instance_pos, "__pos__")
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UNARY(instance_abs, "__abs__")
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static object *
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instance_pow(self, other, modulus)
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instanceobject *self;
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object *other, *modulus;
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{
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object *func, *arg, *res;
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if ((func = instance_getattr(self, "__pow__")) == NULL)
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return NULL;
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if (modulus == None)
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arg = mkvalue("O", other);
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else
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arg = mkvalue("(OO)", other, modulus);
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if (arg == NULL) {
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DECREF(func);
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return NULL;
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}
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res = call_object(func, arg);
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DECREF(func);
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DECREF(arg);
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return res;
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}
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static int
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instance_nonzero(self)
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instanceobject *self;
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@ -922,7 +1004,7 @@ static number_methods instance_as_number = {
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(binaryfunc)instance_div, /*nb_divide*/
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(binaryfunc)instance_mod, /*nb_remainder*/
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(binaryfunc)instance_divmod, /*nb_divmod*/
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(binaryfunc)instance_pow, /*nb_power*/
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(ternaryfunc)instance_pow, /*nb_power*/
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(unaryfunc)instance_neg, /*nb_negative*/
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(unaryfunc)instance_pos, /*nb_positive*/
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(unaryfunc)instance_abs, /*nb_absolute*/
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