[Twisted-Python] logging

[Jamu Kakar]

Hi,

On Thu, Jun 13, 2013 at 6:41 PM, Facundo Batista
<facundobatista at gmail.com> wrote:
> Mmm... which is the problem with doing:
>
> log.msg("Foo happened. Relevant information includes: "
>              "bar=%s baz=%s boz=%s", bar, baz, boz)
>
> Is way more readable, and in the practice the code will just need to
> do something like:
>
> def msg(format_string, *args):
>     try:
>         line = format_string % args
>     except:
>         # something clever
>
> No regexes involved, and very cheap in the case where it works.
>
> And this is a personal opinion: the "working way" (where programmed
> coded all ok) should be as cheap as possible. If something is wrong
> with the logging line, it must not crash, and I don't care if it's
> expensive, but that line will be fixed, and will work ok, and from
> there to the future it will be cheap.

You might be interested in logfmt (which has implementations for Ruby,
Javascript and Go at least):

  https://github.com/jkakar/logfmt-python

The example above could be written in a logfmt-compatible way as:

  log.msg("message=Foo happened bar=%s baz=%s boz=%s", bar, baz, boz)

This is as readable as what you have above while being a touch easier
to parse.  The main point that logs are data and should emitted in a
way that makes consuming them easy is a good one regardless of the
format you choose.  I do wonder if logfmt is unnecessary and if simply
dumping JSON objects would be just as good... logfmt is slightly
prettier but the JSON approach has the advantage of having a parser
available in basically every language anyone would ever care about.

Thanks,
J.