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I'm new to C programming and I have this simplified code: typedef struct Sprite {
int w;
int h;
Transform transform;
}
typedef struct SinCos {
float sin;
float cos;
}
typedef struct Transform {
Vec2 pos; // position
SinCos r; // rotation
}
typedef struct Vec2 {
float x;
float y;
}
static const struct mrb_data_type mrb_vec2_data_type = {"Vec2", mrb_free };
static mrb_value mrb_vec2_initialize(mrb_state* mrb, mrb_value self)
{
Vec2* vec = (Vec2*) mrb_malloc(mrb, sizeof(Vec2));
DATA_PTR(self) = vec;
DATA_TYPE(self) = &mrb_vec2_data_type;
return self;
}
static const struct mrb_data_type mrb_sprite_type = {
"Sprite", mrb_free
};
static mrb_value mrb_sprite_initialize(mrb_state* mrb, mrb_value self)
{
Sprite* sprite = (Sprite*) mrb_malloc(mrb, sizeof(Sprite));
*sprite = sprite_defaults();
DATA_PTR(self) = sprite;
DATA_TYPE(self) = &mrb_sprite_type;
return self;
}
static mrb_value mrb_sprite_get_transform(mrb_state* mrb, mrb_value self)
{
Sprite* sprite = DATA_PTR(self);
return mrb_obj_value(Data_Wrap_Struct(mrb, mrb_transform_class, &mrb_sprite_type, &sprite->transform));
}Basically, I have a 2D framework that has a What is the correct way to expose and wrap those structs? I think ideally I'd like to have a |
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Replies: 1 comment 13 replies
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To maintain a reference from a mrb_value sprite_obj = ...;
mrb_value transform_obj = ...;
mrb_sym iv_name = mrb_intern_lit(mrb, "owner");
mrb_iv_set(mrb, transform_obj, iv_name, sprite_obj);Note that |
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@dearblue What I actually ended up doing is having two types for https://github.com/pusewicz/mruby-cute/blob/main/src/transform.c#L18-L26 https://github.com/pusewicz/mruby-cute/blob/main/src/transform.c#L53-L61 Getting the transform for a Sprite: Thoughts? |
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I have a question. If the timing of freeing the |
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@dearblue The transform struct is not actually a pointer so no need to free it. It gets freed when the whole CF_Sprite gets deallocated: https://github.com/RandyGaul/cute_framework/blob/master/include/cute_sprite.h#L190 |
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If so, it must not be free at the same time as destroying the mrb_iv_set(mrb, transform_obj, iv_name1, sprite_obj); // NEED
mrb_iv_set(mrb, sprite_obj, iv_name2, transform_obj); // This case is for caching |
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@dearblue Thanks again for the response! diff --git i/src/sprite.c w/src/sprite.c
index 436f8ed..945377b 100644
--- i/src/sprite.c
+++ w/src/sprite.c
@@ -313,7 +313,8 @@ static mrb_value mrb_cf_sprite_get_transform(mrb_state* mrb, mrb_value self)
}
// Create a new transform object
- transform_obj = mrb_cf_transform_wrap_nested(mrb, &sprite->transform);
+ transform_obj = mrb_cf_transform_wrap(mrb, &sprite->transform);
+ mrb_iv_set(mrb, transform_obj, mrb_intern_lit(mrb, "sprite"), self);
mrb_iv_set(mrb, self, iv_name, transform_obj);
return transform_obj;This seems to work, except I get a crash when closing the app: Which makes sense, because https://github.com/pusewicz/mruby-cute/blob/main/src/transform.c#L9 here the data will not actually be a pointer that can be freed, right? |
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I think this is correct, + mrb_iv_set(mrb, transform_obj, mrb_intern_lit(mrb, "sprite"), self);Is this not a mistake? - transform_obj = mrb_cf_transform_wrap_nested(mrb, &sprite->transform);
+ transform_obj = mrb_cf_transform_wrap(mrb, &sprite->transform); |
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@dearblue You are right, that was a mistake. But then, what's the point of having |
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In general, it is not possible to pre-free only a portion of the area allocated by Since the |
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If so, it must not be free at the same time as destroying the
Transforminstance.All that is required is to set the
Spriteinstance to an instance variable of theTransforminstance.