[Python-Dev] PEP 8 updates/clarifications (original) (raw)

Barry Warsaw barry at python.org
Wed Dec 14 20:59:36 CET 2005

On Tue, 2005-12-13 at 07:26 -0500, Jim Fulton wrote:

I'd add somewhere: "If in doubt, chose non-public. You can always change your mind later."

Added.

> We don't use the term "private" here, since no attribute is really > private in Python (without a generally unnecessary amount of work). > However, another category of attribute are those which, while not being > public, are intended for use by subclasses (often called "protected" in > other languages). Some classes are designed to be inherited from, > either to extend or modify aspects of the class's behavior. When > designing such a class, take care to make explicit decisions about which > attributes are public, which are non-public but useful for subclasses, and > which are truly only to be used by your base class. A useful term might be "subclass API". Decide which non-public attributes are part of the subclass API.

Excellent suggestion, thanks. I like the term "subclass API". Added.

> - For simple public data attributes, it is fine to expose just the > attribute name, without complicated accessor/mutator methods. Keep in > mind that Python provides an easy path to future enhancement, should > you find that a simple data attribute needs to grow functional > behavior. In that case, use properties to hide functional > implementation behind simple data attribute access syntax. > > Note 1: Properties only work on new-style classes. > > Note 2: Try to keep the functional behavior side-effect free, although > side-effects such as caching are generally fine.

Personally, I'd actively discourage use of trivial accessors. Simple attribute access is not only "fine", IMO, but it is much better than trivial accessors. This is an important point, IMO, because, in my experience, the vast majority of accessors are trivial.

I've changed "fine" to "best".

-Barry

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