Re: How to debug modification to a variable value?

[Richard Stallman]

    It wouldn't be terribly hard to add one, I think.

It would be very bad to use this hook for anything bug debugging,
since it means that setting a variable could do anything whatsoever.
So if such a featur one is added, it will be very important to make
sure it isn't used except for debugging.

One way is to design the feature so it always calls the debugger
when activated.  For instance, if a certain flag is set in a symbol,
then setting its value or function slot calls the debugger.