python易忘知识点

一，property将方法变为属性

class Student(object):

    def get_score(self):
        return self._score

    def set_score(self, value):
        if not isinstance(value, int):
            raise ValueError('score must be an integer!')
        if value < 0 or value > 100:
            raise ValueError('score must between 0 ~ 100!')
        self._score = value
S1=Student()
S1.set_score(59)
print(S1.get_score())


class Student(object):
    @property  #把方法变为属性
    def get_score(self):
        return self._score

    def set_score(self, value):
        if not isinstance(value, int):
            raise ValueError('score must be an integer!')
        if value < 0 or value > 100:
            raise ValueError('score must between 0 ~ 100!')
        self._score = value


S1 = Student()
S1.set_score(59)
print(S1.get_score)

二，sys.argv

第一个元素sys.argv[0] 是程序本身，随后是外部给的参数

test.py代码

三，命令行解析

import argparse
parser = argparse.ArgumentParser()
parser.parse_args()

import argparse
parser = argparse.ArgumentParser()
parser.add_argument("echo")
args = parser.parse_args()
print（args.echo）

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('square', help="display a square of a given number")
args=parser.parse_args()
print(args.square**2)

发生类型错误 

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('square', help="display a square of a given number",type=int)
args=parser.parse_args()
print(args.square**2)

import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--square', help="display a square of a given number",type=int)
args=parser.parse_args()
print(args.square**2)