no7dw/py-practice

Compare Python with Node.js

all Node.js knowledge is in ()

basic

• list (array)

  • method:insert() /pop() / 直接赋值update

  namelist = ['Deng', 'Wei'] namelist[0] 'Deng' namelist[1] 'Wei' namelist[2] Traceback (most recent call last): File "", line 1, in IndexError: list index out of range namelist[-1] 'Wei'

• tuple (more than const array --- Object.freeze)

  nametuple=('Deng','Wei') nametuple[0] 'Deng' nametuple[2] Traceback (most recent call last): File "", line 1, in IndexError: tuple index out of range nametuple[-1] 'Wei' nametuple[-1]='Wei2' Traceback (most recent call last): File "", line 1, in TypeError: 'tuple' object does not support item assignment

• dict (json key-value)

  • method:pop() /直接赋值update/赋值新的key value

  IDNamedict={'001':'dengwei','002':'david','003':'wade'} IDNamedict['001'] 'dengwei' IDNamedict['004'] Traceback (most recent call last): File "", line 1, in KeyError: '004' IDNamedict['004']='xxx'

• set(Set)

  • method:add() /del()

• generator(generator)

• isinstance/type(type of)

  isinstance(namelist,list) True isinstance(namelist,tuble) Traceback (most recent call last): File "", line 1, in NameError: name 'tuble' is not defined isinstance(namelist,tuple) False type(namelist) <class 'list'> type(namelist) is list True

class

• inheritance(father) (vs extends)

  class Bird(Animal): pass

• multiple inheritance(mixin： Object.assign(obj.prototype,mixin mixwith.js))

  class MyUDPServer(UDPServer, ThreadingMixIn): pass

package install

• https://pypi.python.org (npmjs.org)
• install command: easy_install/pip (npm )
• pip3 install -r requirements.txt (npm i)
  • pip3 install gunicorn (npm install lodash)

unittest

• package

  • unitest(mocha) -- internal package

    • run command
      • $python3 test_xx.py
        • 留意
          • 名字命名要 以test_ 开头，class 内的函数 以 test_xx 开头
          • class TestXXX(unittest.TestCase)
      • $python3 -m unittest discover test # test 目录自发现
      • mock(nock)

    	from mock import MagicMock
    	thing = ProductionClass()
    	thing.method = MagicMock(return_value=3)
    	self.assertEqual(thing.method(), 3)
    

  • py.test(mocha) -- 3rd testing framework

    • run command

      py.test

    • test case

      • 使用 @pytest.mark.parametrize 初始参数化test case 的参数
      • 使用 (teardown_class/teardown_module、setup_class/setup_module)[https://docs.python.org/3/library/unittest.html#unittest.TestCase.tearDown] 来做准备工作&销毁工作

decorator

• some only in ts

important internal package

import 3rd package

data processing

• package
  • pydash(lodash)
  • panda(more than mathjs)

async

• async/await(async/await)
  • package
    • asyncio
    • aiohttp
    • threading

db

• package
  • mysql-connector-python/mysql-connector(sequelize)
  • pymongo(mongoose)

web framework:

• flask(expressjs)
  • demo
  • FLASK_DEBUG=1 FLASK_APP=hello-world.py flask run (node-dev/nodemon)# auto reload

from python2.7 to python3 causion: may need to handle somelib version change

`
	2to3 2.py -w 
`

property annotation

```
    class Human():
        def __init__(self):
            pass 

        @property 
        def name(self):
            return "Wade"

```

相当于为了实现作为属性的访问：

```
    h =  Human()
    #print(h.name()) #instead of this
	print(h.name)
```