logging module and trailing newlines

[Russell Warren]

I was just setting up some logging in a make script and decided to
give the built-in logging module a go, but I just found out that the
base StreamHandler always puts a newline at the end of each log.
There is a comment in the code that says "The record is then written
to the stream with a trailing newline [N.B. this may be removed
depending on feedback]"... I guess there wasn't the feedback to drive
the change.

All I'm after is the ability to log things like...

Compiling 'shrubbery.c'... [DONE]

where the "[DONE]" was added later in time than the "Compiling...",
and the output goes to both stdout and to a log file. ie: I want to
tee my print statements and keep the ability to skip the trailing
newline. I had rolled my own primitive version than decided to try
the logging module for kicks.

Anyone have a suggestion on how to get logging to work like this? Or
know of a way to tee in Windows without forcing other users to install
a tee package?

[Peter Otten]

Russell Warren wrote:

All I'm after is the ability to log things like...

Compiling 'shrubbery.c'... [DONE]

where the "[DONE]" was added later in time than the "Compiling...", and
the output goes to both stdout and to a log file. ie: I want to tee my
print statements and keep the ability to skip the trailing newline. I had
rolled my own primitive version than decided to try the logging module for
kicks.

Anyone have a suggestion on how to get logging to work like this? Or know
of a way to tee in Windows without forcing other users to install a tee
package?

(1) Logging

If you are too lazy to subclass you can monkey-patch:

>>import logging
def emit(self, record):

.... msg = self.format(record)
.... fs = "%s" if getattr(record, "continued", False) else "%s\n"
.... self.stream.write(fs % msg)
.... self.flush()
....

>>logging.StreamHandler.emit = emit
continued = dict(continued=True)
logging.error("Compiling... ", extra=continued); logging.error("[Done]")

ERROR:root:Compiling... ERROR:root:[Done]

(2) Teeing

"Primitive", but should work:

>>class Stream(object):

.... def __init__(self, *streams):
.... self.streams = streams
.... def write(self, s):
.... for stream in self.streams:
.... stream.write(s)
.... def flush(self):
.... for stream in self.streams:
.... stream.flush()
....

>>import sys
stream = Stream(sys.stdout, sys.stderr)
print >stream, "Compiling...",

Compiling...Compiling...>>>

I'd probably go with the latter.

Peter

[Russell Warren]

Both are very good responses... thanks! I had forgotten the ease of
"monkey-patching" in python and the Stream class is certainly cleaner
than the way I had been doing it.

On Oct 3, 3:15 am, Peter Otten <[e-mail]:

Russell Warren wrote:

All I'm after is the ability to log things like...

Compiling 'shrubbery.c'... [DONE]

where the "[DONE]" was added later in time than the "Compiling...", and
the output goes to both stdout and to a log file. ie: I want to tee my
print statements and keep the ability to skip the trailing newline. I had
rolled my own primitive version than decided to try the logging module for
kicks.

Anyone have a suggestion on how to get logging to work like this? Or know
of a way to tee in Windows without forcing other users to install a tee
package?

(1) Logging

If you are too lazy to subclass you can monkey-patch:

>import logging
def emit(self, record):

... msg = self.format(record)
... fs = "%s" if getattr(record, "continued", False) else "%s\n"
... self.stream.write(fs % msg)
... self.flush()
...>>logging.StreamHandler.emit = emit

>continued = dict(continued=True)
logging.error("Compiling... ", extra=continued); logging.error("[Done]")

ERROR:root:Compiling... ERROR:root:[Done]

(2) Teeing

"Primitive", but should work:

>class Stream(object):

... def __init__(self, *streams):
... self.streams = streams
... def write(self, s):
... for stream in self.streams:
... stream.write(s)
... def flush(self):
... for stream in self.streams:
... stream.flush()
...>>import sys

>stream = Stream(sys.stdout, sys.stderr)
print >stream, "Compiling...",

Compiling...Compiling...>>>

I'd probably go with the latter.

Peter