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Design doc for life-cycle of MB objects for JS
author Thinker K.F. Li <thinker@codemud.net>
date Mon, 23 Aug 2010 10:23:30 +0800
parents 763a4e2bbd85
children d8764f10e141
comparison
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738:4f9773574234 739:4916c3a3fe3c
11 #include "mbfly_njs.h" 11 #include "mbfly_njs.h"
12 12
13 #ifndef ASSERT 13 #ifndef ASSERT
14 #define ASSERT(x) 14 #define ASSERT(x)
15 #endif 15 #endif
16
17 /*! \page jsgc How to Manage Life-cycle of Objects for Javascript.
18 *
19 * The life-cycle of MadButterfly ojects are simple. A object is live
20 * when it is created and dead when it is free. When a coord or shape
21 * is free, it is also removed from the tree. There is not way to
22 * remove a coord or a shape without freeing it. So, if you want to
23 * remove a coord or a shape object from the tree, you can only free
24 * it.
25 *
26 * Javascript, in conventional, does not free an object. It has GC,
27 * the engine, being used, will free an object if it is no more
28 * referenced. So, we had better provide a removing function, but
29 * actually free an object. In idea situation, a new MB object would
30 * be created for and attached on the JS object, when an object added
31 * back to the tree. But, it means we need to keep states of an
32 * object and create a new one with the same states later. It is
33 * complicated. So, once an object is removed, it is invalidated.
34 *
35 * I hope someone would implement a higher abstract layer, in JS, to
36 * implement the idea model that recreate a new object when an
37 * invalidated JS object being added back.
38 *
39 * An invalid object is the one with NULL internal field and obj.valid
40 * == false. The binding of MadButterfly hold a reference to every
41 * object added to the tree of a mbrt (runtime object), and remove the
42 * reference and invalidate it when it being removed.
43 *
44 * The binding also hold a weak reference to every object, it free the
45 * object when the callback of the weak reference being called and it
46 * being valid. If the object is invalid, the callback does nothing.
47 */
16 48
17 using namespace v8; 49 using namespace v8;
18 50
19 /*! \defgroup xnjsmb_coord JS binding for coord objects. 51 /*! \defgroup xnjsmb_coord JS binding for coord objects.
20 * \ingroup xnjsmb 52 * \ingroup xnjsmb