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()