BlockBasedOOP.c

struct FooReturn {
    int (^getBaz)(void);
    void (^setBaz)(int newValue);
};

struct FooReturn foo(int initialBazValue) {
    __block int baz = initialBazValue;
    
    int (^getBaz)(void) = ^{
        return baz;
    };
    
    void (^setBaz)(int newValue) = ^(int newValue){
        baz = newValue;
    };
    
    // In both of these blocks, identifier `baz` refers
    // to THE SAME object (location in memory).
    // Since `baz` is of `__block` storage type,
    // it's dynamically allocated
    // somewhere not in the `foo`'s stack frame.
    
    /* Pre-C99
    struct FooReturn res;
    res.getBaz = getBaz;
    res.setBaz = setBaz;
     */
    
    // This shit requires C99+ though
    return (struct FooReturn){
        getBaz,
        setBaz
    };
}

void bar() {
    struct FooReturn fooObj = foo(3);
    
    int currValue = fooObj.getBaz(); // 3
    fooObj.setBaz(5);
    int newValue = fooObj.getBaz(); // 5
}