Constructs a reactor object that notifies when an object is added to, modified in, or erased from a drawing database

The vlr-acdb-reactor function constructs a database reactor object.

(vlr-acdb-reactor data callbacks)



Any AutoLISP data to be associated with a reactor object; otherwise nil, if no data.


A list of pairs of the following form:

(event-name . callback_function)

where event-name is one of the symbols listed in the “Database reactor events” table below, and callback_function is a symbol representing a function to be called when the event fires. Each callback function accepts two arguments:

reactor_object The VLR object that called the callback function

obj The database object (AutoLISP entity) associated with the event

Database reactor events




An object has been appended to the drawing database.


An object has been detached from the drawing database, e.g., by using UNDO.


A detached object has been restored in the drawing database, e.g., by using REDO.


An object is about to be changed.


An object has been changed.


An object has been flagged as being erased.


An object's erased-flag has been removed.