how to cancel a special operation with reactor or something else?

[Anonymous]

I want to do such work below,

there is a AcdbLine and a AcdbCircle in a dwg, if I move the circle exactly to the end of the line, then dothing, but if I move the circle to other place (not on the two ends of the line),then the circle automatically goes back to its old postion.   but how to implement this with objectARX?  I guess some reactor object shoud be used.

[Alexander.Rivilis]

If I understand you correctly, then we are talking about Associative Framework.

You can read ObjectARX for AutoCAD 2013: Developer Guide > Advanced Topics > Advanced Topics > Associative Framework.

Also useful topics:

Associative Framework: How to delete constraints applied to a specific entity?

A simplified .NET API for accessing AutoCAD parameters and constraints

[Anonymous]

it is hard for me to tell something in English correctly.

I want to cancel some operation.   For example , I draw a line in Autocad, then I move one end of the line to a new place, is there any way to cancel this operation(move one end to a new place) using objectARX (2008 if possible)

[Alexander.Rivilis]

To understand that it is not easy you can read (completely):

Locking an Entity in AutoCAD using ObjectARX