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Diffstat (limited to 'Doc/howto/logging-cookbook.rst')
| -rw-r--r-- | Doc/howto/logging-cookbook.rst | 17 |
1 files changed, 11 insertions, 6 deletions
diff --git a/Doc/howto/logging-cookbook.rst b/Doc/howto/logging-cookbook.rst index 6f8a693..aa4a7df 100644 --- a/Doc/howto/logging-cookbook.rst +++ b/Doc/howto/logging-cookbook.rst @@ -972,12 +972,13 @@ Use of alternative formatting styles When logging was added to the Python standard library, the only way of formatting messages with variable content was to use the %-formatting method. Since then, Python has gained two new formatting approaches: -string.Template (added in Python 2.4) and str.format (added in Python 2.6). +:class:`string.Template` (added in Python 2.4) and :meth:`str.format` +(added in Python 2.6). -Logging now (as of 3.2) provides improved support for these two additional -formatting styles. The :class:`Formatter` class been enhanced for Python 3.2 to -take an additional, optional keyword parameter named ``style``. This defaults -to ``'%'``, but other possible values are ``'{'`` and ``'$'``, which correspond +Logging (as of 3.2) provides improved support for these two additional +formatting styles. The :class:`Formatter` class been enhanced to take an +additional, optional keyword parameter named ``style``. This defaults to +``'%'``, but other possible values are ``'{'`` and ``'$'``, which correspond to the other two formatting styles. Backwards compatibility is maintained by default (as you would expect), but by explicitly specifying a style parameter, you get the ability to specify format strings which work with @@ -1068,7 +1069,7 @@ they're declared in a module called ``wherever``): .. code-block:: pycon >>> from wherever import BraceMessage as __ - >>> print(__('Message with {0} {1}', 2, 'placeholders')) + >>> print(__('Message with {0} {name}', 2, name='placeholders')) Message with 2 placeholders >>> class Point: pass ... @@ -1083,6 +1084,10 @@ they're declared in a module called ``wherever``): Message with 2 placeholders >>> +While the above examples use ``print()`` to show how the formatting works, you +would of course use ``logger.debug()`` or similar to actually log using this +approach. + One thing to note is that you pay no significant performance penalty with this approach: the actual formatting happens not when you make the logging call, but when (and if) the logged message is actually about to be output to a log by a |