Debug instrumentation on demand

[toivoh]

There should be a way to mark e.g. a method as debugable, without instrumenting it per default.
Such a method would become instrumented once the user steps into an invocation of it. Debug info would have to be kept from the start, but the method could hopefully run at normal speeds for normal invocations. This might only work for top-level methods. It should hopefully allow to mark much greater parts of code for debugging.

[cpitclaudel]

Alternatively, would it be an option to create a juliadb binary that one could invoke as juliadb <some-source-file> and to instrument everything in a source file and start debugging it?