[erlang-questions] Why no ?FUNCTION macro

G Bulmer gbulmer@REDACTED
Thu Sep 20 16:35:55 CEST 2007


Adam

I'm just curious, but is the requirement to get an atom (or string)  
as a macro expansion, e.g. available at compile time, or would it be  
okay if it were available from a function at run-time (where you  
could also use the full power of Erlang to manipulate the value)?

As Richard Carlsson explained, knowing the function name at pre- 
processor time may be quite difficult. Further, it may have no  
obvious meaning for  anonymous fun's (lambda expressions).

Specifically, I'm curious to know if you need to use the function  
name value in debug-style messages (and hence as late as run-time may  
be okay), or whether you really need to do something during pre- 
processor or compile time (e.g. like C tokenising to build lexically  
new names).

As I said, this is only curiosity, but if the need is a run-time  
name, maybe an ingenious function to dig through the stack trace  
returned by erlang:get_stacktrace() would be workable.

I was looking at Joe's Book at try_test.erl in section 4.9 which  
gives a way to get this information. I realise this is a bit ugly,  
but I haven't found how to get a stack trace *without* generating an  
exception.

On the basis that the information appears to be available at run-time  
to erlang:get_stacktrace(), then maybe there is a way to get it  
without generating an exception, and I'd like to know. If not  
available now, it does look like a candidate for a future release,  
and I'd be happy with a run time function, but I realise that may be  
inadequate for your need.

Garry


> Date: Thu, 20 Sep 2007 13:30:03 +0200
> From: "Adam Lindberg" <adam@REDACTED>
> Subject: [erlang-questions] Why no ?FUNCTION macro
> ...
> Why is there no ?FUNCTION macro? If it is possible to do ?MODULE  
> and ?LINE
> it should be possible to do ?FUNCTION too?
>
> Cheers!
> Adam



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