[Twisted-Python] Log output formatting (was Re: logging question)

Kevin Horn kevin.horn at gmail.com
Thu Nov 17 16:10:18 EST 2011

On Wed, Nov 16, 2011 at 2:27 PM, Don Dwiggins <ddwiggins at advpubtech.com>wrote:

> **
> On 11/15/2011 8:57 AM, Christopher Armstrong wrote:
> If you pass a 'system' kwarg to log.msg then it will go in that field.
>  log.msg("hi", system="stuff") results in <date> [stuff] hi
> This triggered me to look further into what LogPublisher.msg does, since
> I've long wanted to customize the format of the output.  I found what I
> wanted in
> http://twistedmatrix.com/documents/current/api/twisted.python.log.ILogObserver.html:
> In msg(), the message gets added to the kwargs dictionary (along with a
> timestamp called 'time'), and that dict is passed to LogObserver.emit,
> which uses textFromEventDict() to create what's actually output.  This
> dictionary has the following keys recognized by textFromEventDict:
>    - message: A tuple of str containing messages to be logged.
>    - system: A str which indicates the "system" which is generating this
>    event.
>    - isError: A bool indicating whether this event represents an error.
>    - failure: A failure.Failure<http://twistedmatrix.com/documents/current/api/twisted.python.failure.Failure.html>instance, required
>    if the event is an error.
>    - why: Used as header of the traceback in case of errors.
>    - format: A string format used in place of message to customize the
>    event. The intent is for the observer to format a message by doing
>    something like format % eventDict.
> So, for example, you could do log.msg(format='....', foo='stuff',
> bar='things')
> I suggest that this be added to the documentation string of the msg()
> method and
> http://twistedmatrix.com/documents/current/core/howto/logging.html.
> --
> Don Dwiggins
> Advanced Publishing Technology
Please open a ticket for this, so it doesn't get lost.


Kevin Horn
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