Bug 13406 – Feature request: @trace attribute for automatic tracing, OR @(scope, scopeFn)

There have been several proposals for logging in phobos, but I have not seen a request for tracing. By tracing I mean on-the-fly recording of function entry+args and exit+return, sent to a logging framework of some kind. Other languages use aspect-oriented programming (Java) and before/after methods (lisp) to apply this automatically to all code in a project. I believe that a @trace function attribute could satisfy this very well. Desired behavior: @trace int foo(string bar) { ... blah ... } ...magically becomes... int foo(string bar) { traceFunctionEnter(__LINE__, __FILE__, __MODULE__, __FUNCTION__, __PRETTYFUNCTION__, [ bar ]); scope(success) { traceFunctionExitSuccess(__LINE__, __FILE__, __MODULE__, __FUNCTION__, __PRETTYFUNCTION__, result); } scope(failure) { traceFunctionExitFailure(__LINE__, __FILE__, __MODULE__, __FUNCTION__, __PRETTYFUNCTION__, result); } ... blah ... } Add the ability to set traceFunctionEnter / traceFunctionExitFailure / traceFunctionExitSuccess and a logging framework could automagically plug in and become a tracing framework too. If @trace as a feature is too library-specific, this idea could instead be implemented by something like @(scope, &scopeFn) where scopeFn looks like: void scopeFn(scopeType, __LINE__, __FILE__, __MODULE__, __FUNCTION__, __PRETTYFUNCTION__, [ args ]) ...where scopeType is an enum value meaning "in", "success", or "failure", and args contains either the input parameters or the return (value or exception), respectively.

I have changed my mind. mixins can already accomplish this. Let's not make this a compiler dependency.