Review of Jose Armando Garcia Sancio's std.log

[Geoffrey Biggs]

On 07/03/12 09:59, Andrei Alexandrescu wrote:
> I don't see why the agitation around this particular matter. It's a
> matter of convenience, much like writeln (as opposed to just write).
> Let's admit that it often happens that you want to log some troublesome
> stuff just before throwing an exception with essentially the same
> message, so the thing is shown on the screen and also persisted in the
> log. Without a critical level, the pattern would be:
>
> string message = stuff() + ": " + moreStuff();
> log.error(message);
> throw new Exception(message);
>
> It's nice to encapsulate this frequent pattern, hence:
>
> log.critical(stuff() + ": " + moreStuff());
>
> If you want to log but not throw, use log.error. I don't think the
> response "dont use those libraries either" is meaningful.

That approach means that if I actually do have a fatal error, I can't 
mark it as such. It gets conflated with the non-fatal errors, both in 
the source and in the logging output (which may, for example, be 
filtering for fatal errors to phone someone in the middle of the night 
while errors just send an email). Another point worth considering is 
that I cannot use the fatal level and be able to re-compile my software 
with logging disabled, because that will change the program flow.

Forcing the two semantic concepts (logging and error handling) together 
needlessly restricts the ways the library can be used. It is nice to 
encapsulate frequent patterns, but providing a convenience function that 
throws an error, or a new level ("terminate" or something) is a better 
approach than forcing that pattern on everyone. Based on the name, it's 
a *logging* library, not an error handling library.

Geoff