Implementing std.log

[Jens Mueller]

Andrei Alexandrescu wrote:
> On 05/14/2011 04:56 PM, Michel Fortin wrote:
> >On 2011-05-14 17:31:30 -0400, Jonathan M Davis <jmdavisProg at gmx.com> said:
> >
> >>So, I do think that knowing which thread is logging what could be very
> >>important for some programs, but I don't think that separating the log
> >>files
> >>is necessarily a good idea. If you did, you'd lose timing information
> >>(unless
> >>the time is at the beginning of every log line (which could also be
> >>useful),
> >>but then you'd have to read the times and compare them to see what
> >>happened
> >>before what). So, I'd be all for some options and extra information which
> >>could be added to each log line which would help debugging, but I
> >>don't think
> >>that thread-local logs is a great idea.
> >
> >I'd even go further and question whether it makes sense to have info,
> >warning, and errors be written to separate files.
> >
> >I'll also question whether they should be written to files at all by
> >default (as opposed to stdin and stderr). I'm aware initLogging's
> >documentation says: "If log­ging is ef­fected with­out hav­ing called
> >this func­tion, all pa­ra­me­ters are at their de­fault val­ues and all
> >log­ging is done only to stderr." So basically, I'll get what I want if
> >I never call initLogging, but then I can't control verbosity and other
> >settings using --v and other flags passed as arguments.
> 
> A server app must log to files, no question about that. We'll need
> to add rotation etc. in the future. But I do plan to offer ways to
> manually override defaults, e.g.:
> 
> void main(string[] args)
> {
>     logtostderr = true; // override default
>     initLogging(args);
>     ...
> }

How do you plan to do this?
Because it looks partly what gflags is doing. At least it would be
useful as general feature for handling program options.
I haven't found a way to define flags in a compilation unit as gflags
does. I have code that generates a help string and even reading flags
from a files is easy. But I have no clue yet how to allow declaring
flags in different compilation units. Technically I'd like to allow each
flag that can be handled by std.getopt but I have no idea how to check
whether getopt supports a given flag. If I knew I'd store flags in
associative array where values are Algebratic!(GetoptFlagTypes).

Jens