[Python-checkins] cpython (2.7): Issue 12086: add example showing how to use name mangling.
raymond.hettinger
python-checkins at python.org
Sat Jun 25 16:28:22 CEST 2011
http://hg.python.org/cpython/rev/68bc3c5960a4
changeset: 70973:68bc3c5960a4
branch: 2.7
parent: 70968:0ca8ffffd90b
user: Raymond Hettinger <python at rcn.com>
date: Sat Jun 25 16:28:07 2011 +0200
summary:
Issue 12086: add example showing how to use name mangling.
files:
Doc/tutorial/classes.rst | 22 ++++++++++++++++++++++
1 files changed, 22 insertions(+), 0 deletions(-)
diff --git a/Doc/tutorial/classes.rst b/Doc/tutorial/classes.rst
--- a/Doc/tutorial/classes.rst
+++ b/Doc/tutorial/classes.rst
@@ -553,6 +553,28 @@
without regard to the syntactic position of the identifier, as long as it
occurs within the definition of a class.
+Name mangling is helpful for letting subclasses override methods without
+breaking intraclass method calls. For example::
+
+ class Mapping:
+ def __init__(self, iterable):
+ self.items_list = []
+ self.__update(iterable)
+
+ def update(self, iterable):
+ for item in iterable:
+ self.items_list.append(item)
+
+ __update = update # private copy of original update() method
+
+ class MappingSubclass(Mapping):
+
+ def update(self, keys, values):
+ # provides new signature for update()
+ # but does not break __init__()
+ for item in zip(keys, values):
+ self.items_list.append(item)
+
Note that the mangling rules are designed mostly to avoid accidents; it still is
possible to access or modify a variable that is considered private. This can
even be useful in special circumstances, such as in the debugger.
--
Repository URL: http://hg.python.org/cpython
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