Adding classes to micropython module - micropython

Question

In reference to adding module in micropython, I was trying to create a class which has a local method. In the documentation it is given how to add local methods and that the first argument should be of mp_obj_t type which is the data struct itself. However, I was asking how can I pass extra parameters like other methods? I tried using mp_obj_t * args as second argument but STATIC MP_DEFINE_CONST_FUN_OBJ_1 gives error. I tried the same with STATIC MP_DEFINE_CONST_FUN_OBJ_VAR but it does not support passing mp_obt_t as first argument as STATIC MP_DEFINE_CONST_FUN_OBJ_VAR needs an int. I am quite new, so I was asking how to add methods to classes which can accept arguments?

Answer 1

You need MP_DEFINE_CONST_FUN_OBJ_2, since you have 2 arguments.
Something like
STATIC mp_obj_t my_class_func(mp_obj_t self, mp_obj_t arg) {
if (MP_OBJ_IS_SMALL_INT(lhs)) {
const mp_int_t lhs_val = MP_OBJ_SMALL_INT_VALUE(arg);
//...
} else {
//oops, not an int
}
return mp_const_none;
}
MP_DEFINE_CONST_FUN_OBJ_2(my_class_func_obj, my_class_func);
The best source of samples like this is the source code btw.

Answer 2

To eleaborate on #stijn answer ~ when creating a class, all the MP_DEFINE_CONST_FUN_OBJ_XXXXXX defines work the exact same as they would if you weren't creating a class. The only difference is the first argument of ACTUAL arguments will always refer to self
Here's an example:
mp_obj_t Class_method(mp_uint_t n_args, const mp_obj_t *args) { ... }
That is the standard candidate for:
MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(Class_method_obj, 1, 3, Class_method);
However, in this case args[0] will be self.
Let's have another example.
mp_obj_t Class_method(mp_uint_t n_args, const mp_obj_t *args, mp_map_t *kw_args) { ... }
That's a prime candidate for this define
MP_DEFINE_CONST_FUN_OBJ_KW(Class_method_obj, 2, Class_method);
The only difference in this case is that the first index of allowed_args needs to automatically be handled as self. Nothing about how you do these things changes, except now the first ACTUAL argument (ie not including n_args or any other "helper" argument) needs to automatically be considered as self. That being said, you will NEVER use MP_DEFINE_CONST_FUN_OBJ_0 with a class method. '_0' means "zero arguments" and a class method will never have zero arguments because it will ALWAYS at least have self. This also means that you have to add one to however many expected arguments you have on the python end. If your python version accepts 3 arguments ~
(red, green, blue)
then your C_MODULE define has to start at 4 because it's going to get
(self, red, green, blue)