py: Support instance __call__ method.

py/objtype.c

@@ -338,6 +338,16 @@ STATIC mp_obj_t class_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
     }
 }
 
+STATIC mp_obj_t class_call(mp_obj_t self_in, uint n_args, uint n_kw, const mp_obj_t *args) {
+    mp_obj_class_t *self = self_in;
+    mp_obj_t member = mp_obj_class_lookup(self->base.type, MP_QSTR___call__);
+    if (member == MP_OBJ_NULL) {
+        return member;
+    }
+    mp_obj_t meth = mp_obj_new_bound_meth(member, self);
+    return mp_call_function_n_kw(meth, n_args, n_kw, args);
+}
+
 /******************************************************************************/
 // type object
 //  - the struct is mp_obj_type_t and is defined in obj.h so const types can be made
@@ -474,6 +484,7 @@ mp_obj_t mp_obj_new_type(qstr name, mp_obj_t bases_tuple, mp_obj_t locals_dict)
     o->load_attr = class_load_attr;
     o->store_attr = class_store_attr;
     o->subscr = class_subscr;
+    o->call = class_call;
     o->bases_tuple = bases_tuple;
     o->locals_dict = locals_dict;
     return o;

py/qstrdefs.h

@@ -31,6 +31,7 @@ Q(__repr__)
 Q(__str__)
 Q(__getattr__)
 Q(__del__)
+Q(__call__)
 
 Q(micropython)
 Q(byte_code)

py/runtime.c

@@ -481,12 +481,15 @@ mp_obj_t mp_call_function_n_kw(mp_obj_t fun_in, uint n_args, uint n_kw, const mp
 
     // do the call
     if (type->call != NULL) {
-        return type->call(fun_in, n_args, n_kw, args);
-    } else {
-        nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'%s' object is not callable", mp_obj_get_type_str(fun_in)));
+        mp_obj_t res = type->call(fun_in, n_args, n_kw, args);
+        if (res != NULL) {
+            return res;
         }
     }
 
+    nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_TypeError, "'%s' object is not callable", mp_obj_get_type_str(fun_in)));
+}
+
 // args contains: fun  self/NULL  arg(0)  ...  arg(n_args-2)  arg(n_args-1)  kw_key(0)  kw_val(0)  ... kw_key(n_kw-1)  kw_val(n_kw-1)
 // if n_args==0 and n_kw==0 then there are only fun and self/NULL
 mp_obj_t mp_call_method_n_kw(uint n_args, uint n_kw, const mp_obj_t *args) {

tests/basics/class_call.py

@@ -0,0 +1,18 @@
+class C1:
+    def __call__(self, val):
+        print('call', val)
+        return 'item'
+
+class C2:
+
+    def __getattr__(self, k):
+        pass
+
+c1 = C1()
+print(c1(1))
+
+c2 = C2()
+try:
+    print(c2(1))
+except TypeError:
+    print("TypeError")