python tips
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2022-05-09 12:40:43
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1、enum
Python代码
#!/usr/bin/env python # -*- coding:utf-8 -*- def enum(**enums): return type('Enum', (), enums) Gender = enum(MALE=0,FEMALE=1) print Gender.MALE print Gender.FEMALE
2、检查字符串是否是number
Python代码
s='123456789' s.isdigit()#return True
3、list取交集
Python代码
s=[1,2,3] w=[2,3,4] list(set(s).intersection(w))
4、两个list转成一个dict
Python代码
dict(zip(a,b))
5、singleton
Python代码
def singleton(cls): instances = {} def get_instance(): if cls not in instances: instances[cls] = cls() return instances[cls] return get_instance
第二种tornado IOLoop中使用的单例模式:
Python代码
@staticmethod def instance(): """Returns a global IOLoop instance. Most single-threaded applications have a single, global IOLoop. Use this method instead of passing around IOLoop instances throughout your code. A common pattern for classes that depend on IOLoops is to use a default argument to enable programs with multiple IOLoops but not require the argument for simpler applications:: class MyClass(object): def __init__(self, io_loop=None): self.io_loop = io_loop or IOLoop.instance() """ if not hasattr(IOLoop, "_instance"): with IOLoop._instance_lock: if not hasattr(IOLoop, "_instance"): # New instance after double check IOLoop._instance = IOLoop() return IOLoop._instance
6、list排重
Python代码
{}.fromkeys(list).keys()
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