Sunday, April 11, 2004

Design Principles

In June 1999, Tim Peters channeled Guido and listed 19 guiding principles
for Python's design in a comp.lang.python posting. The principles shouldn't
be taken too seriously, as they're not hard-and-fast constraints and for
each rule you can probably list instances where it's been broken. Still, no
one has had much disagreement with this list of design criteria:

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one -- and preferably only one -- obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than right now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!

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