Pb extended DLL development (super chapter) (VII)

PB An extension of DLL Development （ Super ）（ 7、 ... and ）

(PB The first open development technology in history )

Object instantiation and destruction

Suppose there is PB This is the code ：

uo_json js

js = create uo_json

DLL The code that implements the same function in is ：

OB_INST_ID obInstID = NULL;

if (rt_create_obinst(obThis, (LPTSTR)_T(“uo_json”), &obInstID) == 1)

{

    // Instantiation successful

}

If you want to return the instance to PB

OB_DATA obReturn = {0};

OB_CLASS_HNDL hndl = ob_get_obinst_class_hndl(obThis, obInstID);

OB_CLASS_ID classID =  hndl.class_id ; // Get its type

ob_set_data_obinst(&obReturn, obInstID, classID, OB_INSTVAR_FIELD);

if(obInstID == NULL)

  ob_set_info_nullval(obReturn .info, TRUE); // If the creation fails , It's a null value , To put NULL Mark , In this way PB In the use isnull() or isvalid()  When judging, it will be false

ot_set_return_val(obThis, &obReturn); // Return object instance

Other functions that can instantiate objects are ：

ob_create_obinst

ot_create_obinst_with_name

ot_create_obinst_at_lval

ob_create_object

ob_create_object_using

Yes ot_ The beginning and ob_ Initial function ,ot_ The beginning should be runtime Class function , Than ob_ The beginning should be more advanced , It is recommended to use ot_ Initial function .

After an object instance , Return to PB Environmental Science , You can explicitly   destroy js, If you don't write destroy Code ,PB It will also automatically Destroy it .

DLL It can be destroyed by itself

ob_destroy_obinst(obThis,obInstID);

it is to be noted that , PB The code doesn't know you DLL Inside has been destroyed , Will continue to destroy , Cause program crash . therefore , You don't usually need to call ob_destroy_obinst This destruction function .

I'm thinking ： This destruction leads to a crash , It should be related to the reference count . Only if its reference count is 0 when , Will really destroy . There's a function rtDataCopy Its last parameter indicates whether to increase the reference count . If it is an incoming parameter , We can use rtDataCopy Copy one for your own use , You can use it up ob_destroy_obinst, It won't break down . unfortunately , I can't find where to add this reference count directly . If you know something, please tell me , I can fill this hole .(*(DWORD*)((DWORD)obInstID + 24)) ++; It can increase the count 1, But I dare not use , Still have SDK Functions are more secure to use .

The above is about invisible objects and instantiation and destruction . As for visualization objects , Still PB Drag and drop with the mouse in the design environment ,DLL It is very complicated to implement , I haven't mastered , Not here .

If you are right about system library Interested in relevant development methods , Accessible QQ Group 624409252 Download from the special directory in the sharing DEMO.