请问acdbOpenObject,acdbOpenAcDbObject,acdbOpenAcDbEntity()区别?

王咣生

AcDbEntity, AcDbObject的区别是什么? acdbOpenAcDbEntity(), acdbOpenAcDbObject(), acdbOpenObject() Global Function的区别是什么?
使用时注意些什么?

easypower

1。AcDbEntity, AcDbObject的区别是什么? 答：AcDbEntity继承自AcDbObject，即除AcDbObject所有的属性和方法之外，还增加有自绘方法（属性也不一定），可以说具有图形特性。 2。acdbOpenAcDbEntity(), acdbOpenAcDbObject(), acdbOpenObject() Global Function的区别是什么?
使用时注意些什么? 答：acdbOpenAcDbEntity专用打开AcDbEntity，acdbOpenAcDbObject专用打开AcDbObject，acdbOpenObject会自动根据你的ObjectId所对应实体类型，调用acdbOpenAcDbEntity或acdbOpenAcDbObject。

王咣生

谢谢easypower版主

王咣生

不太明白: rex12:
With acdbOpenAcDbEntity() you can open ONLY Objects derived from AcDbEntity,
With acdbOpenAcDbObject() you can open ONLY Objects NOT derived from AcDbEntity(that is, have no graphics).
acdbOpenObject()-> there are more possibilities. All descriptions you will find in docs.
That is a mention for objects openning. There is no matter if you want to open an AcDb Entity or AcDbObject derived object. Art Cooney:
That's not correct. acdbOpenAcDbObject() will open objects that are derived from AcDbEntity - it will open any type of object. rex12:
well it's may be, I haven't try it, all i have done was to read reference and there that is written.
So the reference is not correct or ...?
Generally, I use acdbOpenObject function to open an object.
Best Regards Art Cooney:
acdbOpenAcDbEntity() checks to see if the object being opened is of a class directly or indirectly derived from
AcDbEntity and returns an error if it is not.
It also takes a reference to an AcDbEntity* as an argument and sets it to point to the opened entity.
acdbOpenAcDbObject will open any object. It takes a reference to an AcDbObject* as AcDbObject* as an argument and
sets it to point to the opened object.
acdbOpenObject() is template function that is implemented for each class and takes a reference to a pointer to that
class and sets it to point to the opened object. This function uses acdbOpenAcDbObject() to do the actual open operation.

王咣生

很好的方法:
Cyrille Fauvel:
I think Art replied on the subject, but just as a matter of coding style
I prefer using AcDbObjectPointer<T> class where T is the class you want to use.
When using this class I do not have to mind about closing the object. AcDbObjectPointer<AcDbLine> myLine (id, AcDb::kForRead);
myLine->setStartPoint(...);
...
// Never call myLine->close()
Ultimately the AcDbObjectPointer<T> is calling acdbOpenAcDbObject() and close for you.

easypower

王咣生发表于2004-9-25 0:31:00回复：（王咣生）回复不太明白: rex12: With acdbOpenAcDbEntity() you can open ONLY Objects derived from AcDbEntity, With acdbOpenAcDbObject() you...

有什么不明白？？？

easypower

王咣生发表于2004-9-25 9:36:00回复：（王咣生）解决方法 很好的方法: Cyrille Fauvel: I think Art replied on the subject, but just as a matter of coding style I prefer using ...

Smart Pointer是很好用的 值得推荐