Review of Jose Armando Garcia Sancio's std.log

[Robert Jacques]

On Wed, 29 Feb 2012 18:13:30 -0600, Richard van Scheijen <dlang at mesadu.net> wrote:

> When logging the severity level should convey a certain insight
> that the developer has about the code. This can be done with a 3
> bit field. These are: known-cause, known-effect and breaks-flow.
>
> This creates the following matrix:
>
> KC KE BF Severity
> =================
> 1  1  0  Trace
> 0  1  0  Info
> 1  0  0  Notice
> 0  0  0  Warning
> 1  1  1  Error
> 0  1  1  Critical
> 1  0  1  Severe
> 0  0  1  Fatal
>
> A known cause is when the developer knows why a log event is
> made. e.g.: if you cannot open a file, you do not know why.
> A known effect is when he/she knows what happens after.
> Basically, you can tell if it is a catch-all by this flag.
>
> When a severity should only be handled by a debugger, the normal
> debug statement should be used. This is in essence a 4th bit.
>
> I hope this helpful in the search for a good level system.
>

vote++

I think establishing a good guideline as to log usage should be part of std.log's documentation. Making the bitflags a part of Severity might help cement this concept. It would also allow self documenting code, like:

log!(knownCause|unknownEffect|breaksFlow)("This is a severe message.");