Topic: UNDO command in vlisp

[Lupo76]

Hello everyone,
I need to use the following code within a reactor

Code: [Select]

(command "_undo" "1")

Unfortunately this is not possible in a reactor.
I then tried with

Code: [Select]

(vl-cmdf "_undo" "1")
but also in this case does not work: no error but does not perform the operation.

Do you have any idea?

[Marc'Antonio Alessi]

Maybe (vlr-undo-reactor data callbacks)?

[Lupo76]

Maybe (vlr-undo-reactor data callbacks)?

I read here: http://help.autodesk.com/view/ACD/2015/ENU/?guid=GUID-184F011B-8B61-4D3F-82F3-06A75C4459AE

but I did not understand how to use it.
I suspect that is not what I need.

I have made a reactor object:

Code: [Select]

(defun reactor_endmodify (notifier-reactor object-object parameter-list)
    (if (and (= (getvar "CMDNAMES") "BREAK")(= var T))
       (progn
           (princ "\nDo not use the command 'BREAK' but use the command 'XXX'")
           (command "_undo" "1") ;<-----ERROR !!!!
       )
       (progn
          ......
          ......
          ......
       )
     )
)


This reactor has many lines of code and in some circumstances intercepts the start of the BREAK command and issues a message such as "Do not use the command 'BREAK' but use the command 'XXX'. This message should not appear every time it is used BREAK command but only in certain circumstances. To explain all the context is a bit difficult ....

Now I would like to use the UNDO command to cancel the operation of the BREAK command.

[roy_043]

Try using a postprocess:
http://www.theswamp.org/index.php?topic=42826.5

[Lupo76]

Try using a postprocess:
http://www.theswamp.org/index.php?topic=42826.5

Very Well!
the post that you indicated was open to me, but at that time I did not realize 100% anyway.
Today, however, is much clearer for me and it works! 

Thank You

[Lupo76]

Here is the correct code:

(vla-sendcommand (vla-get-activedocument (vlax-get-acad-object)) "_.undo 1 ")