mruby-examples/src/using-cdata/using-cdata.c at main · chadowo/mruby-examples · GitHub

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#include <stdio.h>

#include <stdlib.h>

#include <mruby.h>

#include <mruby/class.h>

#include <mruby/data.h>

#include <mruby/value.h>

/* This sample program will teach you how to work with data in MRuby

* Based on this marvelous article: https://dev.to/roryo/storing-c-data-in-an-mruby-class-50k4 */

/* For demonstration purposes we'll work with a imaginary car

* struct, it accepts a char* for both color and type */

typedef struct carData {

char *color;

char *type;

} carData;

/* We need to note the datatype and the function we'll use

* when the object is GC'ed, The "Car" bit is the unique

* identifier, the class name suffices for that, if you use

* custom allocated resources for your data then you'll need

* to define a custom free function that frees your resources,

* however since we don't do that we can just call mrb_free */

static const mrb_data_type carType = { "Car", mrb_free };

/* Car constructor */

static mrb_value mrb_car_new(mrb_state *mrb, mrb_value self) {

char *color, *type;

mrb_get_args(mrb, "zz", &color, &type);

// We initialize our data structure, DATA_PTR is a macro that gives us

// a void*, we want that pointer to point to ourselves, and

// cast it to a carData

carData *instanceCarData = (carData *)DATA_PTR(self);

// If there's a pointer already associated to this instance, free it

if (instanceCarData) {

mrb_free(mrb, instanceCarData);

}

// Initialize the data

mrb_data_init(self, NULL, &carType);

// Allocate heap memory for the data

instanceCarData = (carData *)malloc(sizeof(carData));

// Set the data

instanceCarData->color = color;

instanceCarData->type = type;

// And now we populate the data

mrb_data_init(self, instanceCarData, &carType);

return self;

}

/* This function will summarize the instance car attributes,

* color and type. Thus demonstrating how to get the data

* back */

static mrb_value mrb_car_summarize(mrb_state *mrb, mrb_value self) {

// We initialize the struct that will hold our data

carData *instanceCarData;

// Get the data

Data_Get_Struct(mrb, self, &carType, instanceCarData);

printf("The car's color is: %s\nThe car's type is: %s\n", instanceCarData->color, instanceCarData->type);

return self;

}

int main(int argc, char *argv[]) {

mrb_state *mrb = mrb_open();

if (!mrb) {

fprintf(stderr, "Couldn't initialize MRuby\n");

return 1;

}

struct RClass *carKlass = mrb_define_class(mrb, "Car", mrb->object_class);

MRB_SET_INSTANCE_TT(carKlass, MRB_TT_DATA);

mrb_define_method(mrb, carKlass, "initialize", mrb_car_new, MRB_ARGS_REQ(2));

mrb_define_method(mrb, carKlass, "summarize", mrb_car_summarize, MRB_ARGS_NONE());

// Now we're gonna create a Car object and call its 'summarize' method.

// The args for the car's initialize

const mrb_value args[2] = { mrb_str_new_cstr(mrb, "Red"), mrb_str_new_cstr(mrb, "Sedan") };

// Our car object

mrb_value carObj = mrb_obj_new(mrb, carKlass, 2, args);

// Call the summarize method

mrb_funcall(mrb, carObj, "summarize", 0);

mrb_close(mrb);

return 0;

}

mruby-examples/src/using-cdata/using-cdata.c at main · chadowo/mruby-examples · GitHub

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