python\列表和產生器運算式

標籤：面向過程   war   列表   return   end   函數   while   wal   面向   

一.協程函數的應用

寫一個裝飾器用於讓協程函數不需要輸入再執行一次next()函數

分析: 在裝飾器中產生該協程函數的產生器, 並且執行一次next()函數

def firstNext(func):    def wrapper(*args, **kwargs):        g = func(*args, **kwargs)        next(g)        return g    return wrapper @firstNextdef eater(name):    print("{} start to eat".format(name))    food_list = []    while True:        food = yield food_list        print("{} eat {}".format(name, food))        food_list.append(food) g = eater("egon")print(g.send("包子"))print(g.send("炸醬麵"))

 

 二.面向過程編程

實現 grep -rl ‘python‘ c:/test 的功能

　　一個函數實現

import os def search(dir_name, partten):    g = os.walk(dir_name)    res = {"",}    for i in g:        for j in i[-1]:            file_path = i[0] + "\\" +j            with open(file_path) as f:                for line in f:                    if partten in line:                        res.add(file_path)    for line in res:        if line:            print(line) search("c:\\test", "python")利用產生器來處理import os def firstNext(func):    def wrapper(*args, **kwargs):        g = func(*args, **kwargs)        next(g)        return g    return wrapper @firstNextdef search(target):    while True:        dir_name = yield        g = os.walk(dir_name)        for i in g:            for j in i[-1]:                file_path = i[0] + "\\" +j                target.send(file_path) @firstNextdef opener(target):    while True:        file_path = yield        with open(file_path) as f:            target.send((file_path, f)) @firstNextdef cat(target):    while True:        file_path, f = yield        for line in f:            target.send((file_path, line)) @firstNextdef grep(partten, target):    while True:        file_path, line = yield        if partten in line:            target.send(file_path) @firstNextdef printer():    while True:        file_path = yield        print(file_path) g = search(opener(cat(grep("python",printer()))))g.send("c:\\test")

 

 三.列表產生式，產生器運算式

列表產生式的具體形式

列表 = [處理變數形成列表元素 for迴圈 if判斷 for迴圈2]　　

　　等同於

for迴圈    if判斷            for迴圈            元素=運算式　　　　列表.append(元素)

　　產生器運算式是 列表產生式的中括弧編程圓括弧

　　其中獲得的是一個產生器

　　可以通過 list(獲得的產生器) 來快速產生一個列表

 

 

 

python\列表和產生器運算式