C as an object oriented language

Question

Could you suggest a syntax for the C language to use it in a similar way than an object-oriented language? I know that they cannot be the same and that some keywords aren\'t

Answer 1

The traditional solution is the function pointer struct. I emphasize traditional. I can tell you what sort of code I wrote in PL/I and C years ago, but I don't claim to speak for the state of the 'art' if you can call this art.

There are many variations on this, and the below is a bit of a compromise.

struct SortOfAnAbstractClass {
   int (*function1)(SortOfAnAbstractClass* this, int arg1, int arg2, char * arg3);
   void (*function2)(SortOfAnAbstractClass* this, char *arg);
};

struct SortOfDerived {
   struct SortOfAnAbstractClass base;
   int instanceVariable1;
};

SortOfAnAbstractClass getMeOne() {
     SortOfDerived *d = malloc(sizeof SortOfDerived);
     memset(d, 0, sizeof SortOfDerived);
     d->function1 = myf1;
     d->function2 = myf2;
     return &d->base;
};

and then 'myf1' and 'myf2' cast their 'this' parameters and go to town. You can extend this to look ever more like a full virtual dispatch.

Another common variation from the mists of time:

struct SortOfAClass {
   void *creatorInfo;
   int (*function1)(SortOfAnAbstractClass* this, int arg1, int arg2, char * arg3);
   void (*function2)(SortOfAnAbstractClass* this, char *arg);
};

In this variation, there's no inheritance by inclusion. The derived classes each put their private state into their own object in creatorInfo.