Idempotent patching

[mandarjog]

I am using the following patch to convert unchecked Debug to wrapped by if logging.isDebugEnabled() .
I would like to make this idempotent so it can be repeatedly applied.

How do I do that?

@@
var x expression
@@
-logging.L(x).Debug(...)
+if logging.IsDebugEnabled(x) {
+    logging.L(x).Debug(...)
+}

[abhinav]

Hey @mandarjog, this isn't currently possible.
You basically have to undo and redo the patch to make it idempotent.
The undo catches existing variants, and the redo covers them all:

@@
var x expression
@@
-if logging.IsDebugEnabled(x) {
    logging.L(x).Debug(...)
-}

@@
var x expression
@@
+if logging.IsDebugEnabled(x) {
    logging.L(x).Debug(...)
+}

One of the options that was considered for the language was a ! prefix (in place of - or +) to mean "code here doesn't match this". If implemented, that could work here, although it would still require duplicating some of the patch content:

@@
var x expression
@@
+if logging.IsDebugEnabled(x) {
!if logging.IsDebugEnabled(x) {
    logging.L(x).Debug(...)
!}
+}