Quoting Kevin Reeder <[EMAIL PROTECTED]>: > What's the significance of naming a variable with a single > underscore as its first character? For example, I'm looking at > find.py in the standard library and it has variables named _debug > and _prune.
Basically, it means "These variables are internal and not part of the API; please do not use them in your code because they may change without warning". The reference here is PEP-8, the Python style guide: http://www.python.org/peps/pep-0008.html Excerpt: """ In addition, the following special forms using leading or trailing underscores are recognized (these can generally be combined with any case convention): - _single_leading_underscore: weak "internal use" indicator (e.g. "from M import *" does not import objects whose name starts with an underscore). - single_trailing_underscore_: used by convention to avoid conflicts with Python keyword, e.g. "Tkinter.Toplevel(master, class_='ClassName')". - __double_leading_underscore: class-private names as of Python 1.4. - __double_leading_and_trailing_underscore__: "magic" objects or attributes that live in user-controlled namespaces, e.g. __init__, __import__ or __file__. Sometimes these are defined by the user to trigger certain magic behavior (e.g. operator overloading); sometimes these are inserted by the infrastructure for its own use or for debugging purposes. Since the infrastructure (loosely defined as the Python interpreter and the standard library) may decide to grow its list of magic attributes in future versions, user code should generally refrain from using this convention for its own use. User code that aspires to become part of the infrastructure could combine this with a short prefix inside the underscores, e.g. __bobo_magic_attr__. """ "class-private" (double leading underscore) basically means extra effort is expended in making the variable hard to see. It's still not enforced, though. This is easiest to explain with an example: >>> class Foo(object): ... __x = 3 ... def p(self): ... print self.__x ... >>> f = Foo() >>> f.__x Traceback (most recent call last): File "<stdin>", line 1, in ? AttributeError: 'Foo' object has no attribute '__x' >>> f.p() 3 >>> f._Foo__x 3 Google for python name-mangling if you want to know more about this :-) -- John. _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
