提升python代码的品味

最新推荐文章于 2025-05-19 22:46:04 发布

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本文介绍了几个提升Python代码品味的实例，包括使用next获取循环中符合条件的值、优化缓存写法、执行调用直到满足特定条件以及利用partialmethod改进方法。

优美的python

举几个鲜为人知的例子，却很能提升代码品味。

使用next获取循环中符合条件的值

#bad
a = -1
for i in range(1,10):
    if not i%4:
        a = i
        break


#good
a = next((i for i in range(1,10) if not i % 4), -1)

#比较好的缓存写法

import urllib
from functools import wraps

def cache(func):
    saved = {}
    @wraps(func)
    def deco(*args, **kwargs):
        if not saved[args]: saved[args] = func(*args, **kwargs)
        return saved[args]
    return deco

@cache
def web_lookup(url):
    return urllib.request.urlopen(url).read()

执行调用直到某种情况结束

#bad
res = ""
with open("./help.txt", "r") as f:
    while True:
        buff = f.read(32)
        if buff == "": break
        res += buff

print(res)

#good
import os
from functools import partial
here = os.path.dirname(__file__)

res = ""
with open(os.path.join(here, "help.txt"), "r") as f:
    for buff in iter(partial(f.read, 32), ""):
        res += buff
    
print(res)

#bad
def find(seq, target):
    found = False
    for i, value in enumerate(seq):
        if value == target: 
            found = True
            break
    return found

#good
def find(seq, target):
    for i, value in enumerate(seq):
        if value == target: 
            # found = True
            break
    else:
        return -1
    return i
#第二种方法不用引入found变量

partialmethod的用法

from functools import partialmethod

#实例一
def get_name(self):

return self._name



class Cell(object):


    def __init__(self):

        self._alive = False

        self._name = self.__class__



    @property

    def status(self):

        return self._alive



    def set_state(self, state):

        self._alive = bool(state)

    #partialmethod就是作用于类方法的partial

    set_alive = partialmethod(set_state, True)

    set_dead = partialmethod(set_state, False)

    get_name = partialmethod(get_name)



cell = Cell()

print(cell.status)

cell.set_alive()

print(cell.status)

cell.set_dead()

print(cell.status)

print(cell.get_name())#可以直接调用类外部的类方法


#事例二
class Request(object):

    default_url = "www.baidu.com"

    def request(self, method, url, params=None, data=None):
        print("execute request {} method {}".format(url, method))
        # return self.METHOD_MAP.get(method)

    get = partialmethod(request,"GET")
    post = partialmethod(request,"POST")
    put = partialmethod(request,"PUT")
    delete = partialmethod(request,"DELETE")
    get_default_url = partialmethod(get, default_url)


r = Request()
r.get_default_url()
r.get("shen.com")
r.put("xian.com")