Variable Listener, debug if expr == true

Is there a way to start debug when a variable changes to a specific value, and stop where this happens. I don't mean the conditional breakpoint. (No yellow breakpoints, they're not what i need).

my "breakpoint" is variable, it only stops

< pseudocode >

if expr
  STOP NOW!
end

< /pseudocode >

Note: This code isn't in a .m file

Like stop on error warnings work. But stop on line where isempty(x), or x == 10

[Jan]

This code is not in an M-file? Then why not placing it in an M-file and using conditional breakpoints?

[Andreas Justin]

Thank you for your help! But this isn't what i need!

My Problem is that a variable gets empty at a point where it shouldn't be (and logicly not possible, in my oppinion) and i don't get why, i debugged for several hours but i don't find the reason. and this feature would very help. As i said, like the stop on error occurs.. which would look in pseudo code

if error is happening
   STOP NOW!
end

which you'll already know isn't in the .m file.