[Python-checkins] cpython (merge 3.3 -> default): Merged documentation update from 3.3.
vinay.sajip
python-checkins at python.org
Fri Jan 17 19:36:53 CET 2014
http://hg.python.org/cpython/rev/b62e881129a5
changeset: 88526:b62e881129a5
parent: 88524:30013dbb5bc2
parent: 88525:4d867dc0d5fb
user: Vinay Sajip <vinay_sajip at yahoo.co.uk>
date: Fri Jan 17 18:36:41 2014 +0000
summary:
Merged documentation update from 3.3.
files:
Doc/howto/logging-cookbook.rst | 28 ++++++++++++++++++++++
1 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/Doc/howto/logging-cookbook.rst b/Doc/howto/logging-cookbook.rst
--- a/Doc/howto/logging-cookbook.rst
+++ b/Doc/howto/logging-cookbook.rst
@@ -1918,3 +1918,31 @@
``_`` for the message (or perhaps ``__``, if you are using ``_`` for
localization).
+Examples of this approach are given below. Firstly, formatting with
+:meth:`str.format`::
+
+ >>> __ = BraceMessage
+ >>> print(__('Message with {0} {1}', 2, 'placeholders'))
+ Message with 2 placeholders
+ >>> class Point: pass
+ ...
+ >>> p = Point()
+ >>> p.x = 0.5
+ >>> p.y = 0.5
+ >>> print(__('Message with coordinates: ({point.x:.2f}, {point.y:.2f})', point=p))
+ Message with coordinates: (0.50, 0.50)
+
+Secondly, formatting with :class:`string.Template`::
+
+ >>> __ = DollarMessage
+ >>> print(__('Message with $num $what', num=2, what='placeholders'))
+ Message with 2 placeholders
+ >>>
+
+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
+handler. So the only slightly unusual thing which might trip you up is that the
+parentheses go around the format string and the arguments, not just the format
+string. That’s because the __ notation is just syntax sugar for a constructor
+call to one of the ``XXXMessage`` classes shown above.
--
Repository URL: http://hg.python.org/cpython
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