A little library in C for observing key-value changes.
This project uses doxygen (http://www.stack.nl/~dimitri/doxygen/index.html) for the code documentation. Just point doxygen to the doc/Doxyfile and the html documentation will be generated.
Command line exemple :
cd doc
doxygen DoxyfileThis library uses libmemorymanagement(https://github.com/averello/memorymanagement) internally.
An example of code:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <memory_management/memory_management.h>
#include "ckvo.h"
typedef struct _Object {
int value;
const char *header;
CKVOSupport *kvo;
} Object;
int main(void);
Object *CreateObject(void);
void ObjectDealloc(void *_object);
int *ObjectObtainValue(Object * o);
void ObjectSetValue(Object *o, int value);
const char *ObjectObtainHeader(Object * o);
void ObjectSetHeader(Object *o, const char *const header);
static void ObjectObserveValueForKey(void *const observed,
const void *const oldValue,
const void *const newValue,
const char *const key,
const void *const context);
int main(void) {
CKVOObserver *const valueObserver =
CKVOObserverCreate("value", // key
CKVOObservingOptionsNew, // options
(void *)&main, // context
(void *(*)(const void *const ))ObjectObtainValue, // getter
ObjectObserveValueForKey // callback
);
CKVOObserver *const valueObserverOtherContext =
CKVOObserverCreate("value", // key
CKVOObservingOptionsNew, // options
(void *)&CreateObject, // context
(void *(*)(const void *const ))ObjectObtainValue, // getter
ObjectObserveValueForKey // callback
);
CKVOObserver *const headerObserver =
CKVOObserverCreate("header", // key
CKVOObservingOptionsNew, // options
NULL, // context
(void *(*)(const void *const ))ObjectObtainHeader, // getter
ObjectObserveValueForKey // callback
);
Object *const o = CreateObject();
ckvo_add_observer_for_key(valueObserver, o->kvo);
ckvo_add_observer_for_key(valueObserverOtherContext, o->kvo);
ckvo_add_observer_for_key(headerObserver, o->kvo);
// ObjectObserveValueForKey gets called and prints
// Observed.1.1 0x10073c948, old = 0, new = 2, key = "value", context = main(0x100000da0)
// Observed.1.2 0x10073c948, old = 0, new = 2, key = "value", context = other(0x100000c20)
ObjectSetValue(o, 2);
// ObjectObserveValueForKey gets called and prints
// Observed.2 0x10073c948, old = "(null)", new = "new_header", key = "header", context = 0x0
ObjectSetHeader(o, "new_header");
ckvo_remove_observer_for_key(valueObserver, o->kvo);
ckvo_remove_observer_for_key(valueObserverOtherContext, o->kvo);
ckvo_remove_observer_for_key(headerObserver, o->kvo);
release(valueObserver);
release(valueObserverOtherContext);
release(headerObserver);
release(o);
return 0;
}
static void ObjectObserveValueForKey(void *const observed,
const void *const oldValue,
const void *const newValue,
const char *const key,
const void *const context) {
if (context == (void *)&main) {
printf("Observed.1.1 %p, old = %d, new = %d, key = \"%s\", context = main(%p)\n",
observed, (int)oldValue, (int)newValue, key, context);
}
else if (strcmp(key, "header") == 0) {
printf("Observed.2 %p, old = \"%s\", new = \"%s\", key = \"%s\", context = %p\n",
observed, (const char *)oldValue, (const char *)newValue, key, context);
}
else {
printf("Observed.1.2 %p, old = %d, new = %d, key = \"%s\", context = other(%p)\n",
observed, (int)oldValue, (int)newValue, key, context);
}
}
Object *CreateObject(void) {
Object *const o = MEMORY_MANAGEMENT_ALLOC(sizeof(Object));
o->value = 0;
o->header = "default_header";
o->kvo = CKVOSupportCreate(o);
MEMORY_MANAGEMENT_ATTRIBUTE_SET_DEALLOC_FUNCTION(o, ObjectDealloc);
return o;
}
void ObjectDealloc(void *_object) {
Object *const object = _object;
release(object->kvo);
}
int *ObjectObtainValue(Object * o) {
return (int *)((uint64_t)o->value);
}
void ObjectSetValue(Object *o, int value) {
ckvo_will_change_value_for_key(o->kvo, "value");
o->value = value;
ckvo_did_change_value_for_key(o->kvo, "value");
}
const char *ObjectObtainHeader(Object * o) {
return o->header;
}
void ObjectSetHeader(Object *o, const char *const header) {
ckvo_will_change_value_for_key(o->kvo, "header");
o->header = header;
ckvo_did_change_value_for_key(o->kvo, "header");
}