[plt-dev] logging: strings vs. sexps

At Thu, 19 Feb 2009 16:45:09 -0500, Carl Eastlund wrote:
> On Thu, Feb 19, 2009 at 4:36 PM, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> >
> > Maybe it's not that `log-message' needs to change, but that the
> > `log-error', etc. forms make the wrong thing easy.
> >
> > Currently,
> >
> >  (log-error expr)
> >
> > expands to
> >
> >  (let ([l (current-logger)])
> >    (when (log-level? l 'error)
> >      (log-message l 'error expr (current-continuation-marks))))
> >
> >
> > What if we change it to
> >
> >  (let ([l (current-logger)])
> >    (when (log-level? l 'error)
> >      (let ([v expr])
> >        (log-message l 'error (format "~s" v) v))))
> >
> > ?
> >
> > This changes both the formatting and the value supplied to log
> > receivers by `log-error'. Programmers who want more control over the
> > message and data can still use `log-message'.
> 
> Why not make log-error more like error and printf, such that you can write:
> 
> (log-error "I got a bad value: ~s" v)
> 
> If we're going to use format under the hood anyway, let's give the
> user the benefit.

Technically, that adds an error-checking burden to `log-error', in case
the format string and arguments don't match.
One day, I hope, we'll
figure out a consistent way to tell functions like `printf' that it
should complain about mismatches on behalf of someone else, like
`log-error'.