Re: [Chicken-users] Trace facility

[Alex Shinn]

At Thu, 6 Jan 2005 01:35:23 +0000, Joel Reymont wrote:
> 
> What's a good way to implement a tracing facility? Something where I
> could print messages to stdout but disable the printing by setting a
> variable. 
> 
> Is there's a way to eliminate (compile out) the trace code when building
> a release?

You can conditionally run code based on features specified via the
-feature command (usable in both the interpreter and compiler):

  (cond-expand
    (debug
      (define-macro (debug . args)
        `(fprintf (current-error-port) ,@args)))
    (else
      (define-macro (debug . args) #t)))

The macro makes sure the args are not evaluated so there is zero
overhead when not using "-feature debug".

If using low-level macros then this can also be done with environment
variables instead of features.

-- 
Alex