Python 编程最佳实践

项目结构定义： Sample Repository

This is what Kenneth Reitz recommends.
This repository is available on GitHub.

README.rst
LICENSE
setup.py
requirements.txt
sample/__init__.py
sample/core.py
sample/helpers.py
docs/conf.py
docs/index.rst
tests/test_basic.py
tests/test_advanced.py

---

Very bad

[...]
from modu import *
[...]
x = sqrt(4) # Is sqrt part of modu? A builtin? Defined above?

Better

from modu import sqrt
[...]
x = sqrt(4) # sqrt may be part of modu, if not redefined in between

Best

import modu
[...]
x = modu.sqrt(4) # sqrt is visibly part of modu's namespace

---

Decorators

The Python language provides a simple yet powerful syntax called ‘decorators’. A decorator is a function or a class that wraps (or decorates) a function or a method. The ‘decorated’ function or method will replace the original ‘undecorated’ function or method. Because functions are first-class objects in Python, this can be done ‘manually’, but using the @decorator syntax is clearer and thus preferred.

def foo():
    # do something

def decorator(func):
    # manipulate func
    return func

foo = decorator(foo) # Manually decorate

@decorator
def bar():
    # Do something

# bar() is decorated

---

Bad

items = 'a b c d' # This is a string...
items = items.split(' ') # ...becoming a list
items = set(items) # ...and then a set

Good

count = 1
msg = 'a string'
def func():
    pass # Do something

---

Bad

# create a concatenated string from 0 to 19 (e.g. "012..1819")
nums = ""
for n in range(20):
    nums += str(n) # slow and inefficient
print nums

Good

# create a concatenated string from 0 to 19 (e.g. "012..1819")
nums = []
for n in range(20):
    nums.append(str(n))
print "".join(nums) # much more efficient

Best

# create a concatenated string from 0 to 19 (e.g. "012..1819")
nums = [str(n) for n in range(20)]
print "".join(nums)