写给程序员的 Python 语法快速入门

# 本文目的：总览 Python 的主要语法，并供日后备忘。
# 阅读指南：本文不是文档。通过通读本文，可以了解 Python 基本的语法及一些常用的方法。读者可以将其与其他语言比较，理解其意图与含义。
# 目标读者：具有程序设计基础知识，理解面向对象程序设计基本概念的程序员。

# 若使用 Python 2.X，需设定字符编码以支持中文字符
# -*- coding: UTF-8 -*-
# coding=utf-8

# 模块导入
from math import pi, sqrt # 同时导入多个模块
from re import match as re_match # 重命名

# 类的定义与继承
class Animal:
 __character = "Positive" # 不会经过 "from module_name import *" 导入
 _gender = "Unknown" # 仅表示建议不访问
 """
 文档注释，将在运行时输出
 """
 def __init__(self, name, age):
  self.name = name
  self.age = age

 def shout(self): # 定义类的方法
  print("Sound")

 def live(self):
  print("Alive!")

 def train(behavior): # 修饰器
  def wrap():
   behavior()
  return wrap

 @property # 属性，常用于实现只读特性
 def gender(self):
  return self._gender

 @gender.setter # 实现属性的赋值
 def gender(self, value):
  if value:
   self._gender = value
  else:
   print("Gender not set")

class Wolf(Animal): # 继承于 Animal 类
 def shout(self, default = "Woof!", *sounds, **tones):
  print(default)
  if len(sounds) &gt; 0:
   print(sounds[0])
  print(tones) # {'key':value,}

 def bite(self):
  print("Bite!")

class Dog(Wolf):
 def shout(self):
  print("Woo")

 def bite(self):
  print("Bite?")
  super().shout()

 def __add__(self, other): # 改写 + 运算符。其他运算符也可以类似形式改写
  return Dog(self.name + " and " + other.name, self.age + other.age)

 def __special_behavior(self): # 该方法不会经过 "from module_name import *" 导入
  print("Read books!")

 @classmethod # 定义类方法
 def find_a_puppy(cls, name):
  return cls(name, 0)

 @staticmethod # 定义静态方法
 def find(times)
  print((self.name + "!") * 3)

 @train
 def run():
  print("train running")

# 访问类
puppy = Dog("Puppy", 5)
print(puppy.age) # 5
puppy.live() # Alive!
puppy.shout() # Woo
puppy.bite() # Bite? Woof!
print(_Animal__character) # Positive

# 数组相关
def add_one(x):
 return x + 1

nums = [1,2,3]
result_map = list(map(add_one,nums)) # [2,3,4]
result_filter = list(filter(lambda x:x%2==0,nums)) # [1,3]
nums[0:2:1] # [1,2,3]
nums[1:-1] # [2,3]
first = nums[0]
print(list(range(3))) # [0,1,2]

# Generator 与循环
def infinitive_loop():
 i = 1
 while True:
  yield i
  if True:
   i += 1
  elif False:
   i = 0
  else
   i = 1

for i in infinitive_loop():
 print(i) # 1 2 3...
 if False:
  break
else:
 print("finished without break")

# 集合
num_set = {1,2,3}
print(3 in num_set) # True

# 字典
age_dictionary = {"Alice":17, "Bob":18}
print(age_dictionary["Alice"]

# 多元组
immutable_tuple = ("A","B") # tuple 始终无法被更改
simple_tuple = 1,2,3
a,b = immutable_tuple
a, *b, c = [1,2,3,4] # a 为 1, b 为 [2,3]，c 为 4
b = 5 if a == 2 else 3 # b 为 3 

# 字符串格式
string_format_sample = "String: {0} {1} {x}".format("A","B",x="C")

# 异常处理
try:
 print(1/0)
 assert (2 + 2 == 6), "wrong answer" # AssertionError:wrong answer
 with open("file.txt") as f:
  print(f.read())
 file = open(file.txt)
 print("A" * 3) # AAA
 n = int("9")
except ZeroDivisionError:
 print("Devided by zero"
except (ValueError, TypeError):
 print("Error")
finally:
 file.close()
 print("Finally")
 raise

input("Enter a number: ")

if __name__=="__main__":
 print("Won't be printed if it is imported")

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# 本文目的：总览 Python 的主要语法，并供日后备忘。

# 阅读指南：本文不是文档。通过通读本文，可以了解 Python 基本的语法及一些常用的方法。读者可以将其与其他语言比较，理解其意图与含义。

# 目标读者：具有程序设计基础知识，理解面向对象程序设计基本概念的程序员。

# 若使用 Python 2.X，需设定字符编码以支持中文字符

# -*- coding: UTF-8 -*-

# coding=utf-8

# 模块导入

from math import pi, sqrt # 同时导入多个模块

from re import match as re_match # 重命名

# 类的定义与继承

class Animal:

__character = "Positive" # 不会经过 "from module_name import *" 导入

_gender = "Unknown" # 仅表示建议不访问

"""

文档注释，将在运行时输出

"""

def __init__(self, name, age):

self.name = name

self.age = age

def shout(self): # 定义类的方法

print("Sound")

def live(self):

print("Alive!")

def train(behavior): # 修饰器

def wrap():

behavior()

return wrap

@property # 属性，常用于实现只读特性

def gender(self):

return self._gender

@gender.setter # 实现属性的赋值

def gender(self, value):

if value:

self._gender = value

else:

print("Gender not set")

class Wolf(Animal): # 继承于 Animal 类

def shout(self, default = "Woof!", *sounds, **tones):

print(default)

if len(sounds) > 0:

print(sounds[0])

print(tones) # {'key':value,}

def bite(self):

print("Bite!")

class Dog(Wolf):

def shout(self):

print("Woo")

def bite(self):

print("Bite?")

super().shout()

def __add__(self, other): # 改写 + 运算符。其他运算符也可以类似形式改写

return Dog(self.name + " and " + other.name, self.age + other.age)

def __special_behavior(self): # 该方法不会经过 "from module_name import *" 导入

print("Read books!")

@classmethod # 定义类方法

def find_a_puppy(cls, name):

return cls(name, 0)

@staticmethod # 定义静态方法

def find(times)

print((self.name + "!") * 3)

@train

def run():

print("train running")

# 访问类

puppy = Dog("Puppy", 5)

print(puppy.age) # 5

puppy.live() # Alive!

puppy.shout() # Woo

puppy.bite() # Bite? Woof!

print(_Animal__character) # Positive

# 数组相关

def add_one(x):

return x + 1

nums = [1,2,3]

result_map = list(map(add_one,nums)) # [2,3,4]

result_filter = list(filter(lambda x:x%2==0,nums)) # [1,3]

nums[0:2:1] # [1,2,3]

nums[1:-1] # [2,3]

first = nums[0]

print(list(range(3))) # [0,1,2]

# Generator 与循环

def infinitive_loop():

i = 1

while True:

yield i

if True:

i += 1

elif False:

i = 0

else

i = 1

for i in infinitive_loop():

print(i) # 1 2 3...

if False:

break

else:

print("finished without break")

# 集合

num_set = {1,2,3}

print(3 in num_set) # True

# 字典

age_dictionary = {"Alice":17, "Bob":18}

print(age_dictionary["Alice"]

# 多元组

immutable_tuple = ("A","B") # tuple 始终无法被更改

simple_tuple = 1,2,3

a,b = immutable_tuple

a, *b, c = [1,2,3,4] # a 为 1, b 为 [2,3]，c 为 4

b = 5 if a == 2 else 3 # b 为 3

# 字符串格式

string_format_sample = "String: {0} {1} {x}".format("A","B",x="C")

# 异常处理

try:

print(1/0)

assert (2 + 2 == 6), "wrong answer" # AssertionError:wrong answer

with open("file.txt") as f:

print(f.read())

file = open(file.txt)

print("A" * 3) # AAA

n = int("9")

except ZeroDivisionError:

print("Devided by zero"

except (ValueError, TypeError):

print("Error")

finally:

file.close()

print("Finally")

raise

input("Enter a number: ")

if __name__=="__main__":

print("Won't be printed if it is imported")

写给程序员的 Python 语法快速入门

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《写给程序员的 Python 语法快速入门》有2个想法

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