logging: local functions ==> loss of lineno

[Hellmut Weber]

Am 11.03.2010 12:14, schrieb Peter Otten:
> Hellmut Weber wrote:
>
>> Logging works very well giving the filename and line number of the point
>> where it is called. As long as I use the loggers directly.
>> BUT when I have to wrap the logger call in some other function, I always
>> get file name and line number of the call of the logger inside the
>> wrapping function.
>>
>> Is there a possibility to get this information in this situation too?
>
> The official way is probably to write a custom Logger class that overrides
> the findCaller() method.
>
> Below is a hack that monkey-patches the logging._srcfile attribute to ignore
> user-specified modules in the call stack:
>
> $ cat wrapper.py
> import logging
> import os
> import sys
>
> logger = logging.getLogger()
>
> class SrcFile(object):
>      def __init__(self, exclude_files):
>          self.files = set(exclude_files)
>      def __eq__(self, other):
>          return other in self.files
>
> def fixname(filename):
>      if filename.lower().endswith((".pyc", ".pyo")):
>          filename = filename[:-4] + ".py"
>      return os.path.normcase(filename)
>
> if "--monkey" in sys.argv:
>      print "patching"
>      logging._srcfile = SrcFile([logging._srcfile, fixname(__file__)])
>
> def warn(*args, **kw):
>      logger.warn(*args, **kw)
>
> $ cat main.py
> import logging
> logging.basicConfig(format="%(filename)s<%(lineno)s>: %(message)s")
> import wrapper
> wrapper.warn("foo")
> wrapper.warn("bar")
> wrapper.warn("baz")
>
> $ python main.py
> wrapper.py<23>: foo
> wrapper.py<23>: bar
> wrapper.py<23>: baz
>
> $ python main.py --monkey
> patching
> main.py<4>: foo
> main.py<5>: bar
> main.py<6>: baz
>
> $ python -V
> Python 2.6.4
>
> Peter

Hi Peter,
your hack is exactly what I was looking for.
It permits to configure my logging messages as I want, e.g. using 
different colors for different classes of messages.

I do not yet understand all details WHY it is working but suppose some 
study of the logging module will help me to understand.

Thank you very much

-- 
Dr. Hellmut Weber         mail at hellmutweber.de
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