Pysheet: Python Cheatsheet: Python-Cheatsheet Documentation

What’s New In Python 3
	New in Python3
		print is a function
		String is unicode
		Division Operator
		New dict implementation
		Keyword-Only Arguments
		New Super
		Remove <>
		BDFL retirement
		Not allow from module import * inside function
		Add nonlocal keyword
		Extended iterable unpacking
		General unpacking
		Function annotations
		Variable annotations
		Core support for typing module and generic types
		Format byte string
		fstring
		Suppressing exception
		Generator delegation
		async and await syntax
		Asynchronous generators
		Asynchronous comprehensions
		Matrix multiplication
		Data Classes
		Built-in breakpoint()
		The walrus operator
		Positional-only parameters
		Dictionary Merge
Cheat Sheet
	Style
		Naming
			Class
			Function
			Variable
	From Scratch
		Hello world!
		Python Version
		Ellipsis
		if … elif … else
		for Loop
		for … else …
		Using range
		while … else …
		The do while Statement
		try … except … else …
		String
		List
		Dict
		Function
		Function Annotations
		Generators
		Generator Delegation
		Class
		async / await
		Avoid exec and eval
	Future
		List All New Features
		Print Function
		Unicode
		Division
		Annotations
		BDFL Retirement
		Braces
	Unicode
		String
		Characters
		Porting unicode(s, ‘utf-8’)
		Unicode Code Point
		Encoding
		Decoding
		Unicode Normalization
		Avoid UnicodeDecodeError
		Long String
	List
		From Scratch
		Initialize
		Copy
		Using slice
		List Comprehensions
		Unpacking
		Using enumerate
		Zip Lists
		Filter Items
		Stacks
		in Operation
		Accessing Items
		Delegating Iterations
		Sorting
		Sorted List
		New a List
		Circular Buffer
		Chunk
		Groupby
		Binary Search
		Lower Bound
		Upper Bound
		Lexicographically Order
		Trie
	Set
		Set comprehension
		Uniquify a List
		Union Two Sets
		Append Items to a Set
		Intersection Two Sets
		Common Items from Sets
		Contain
		Set Diff
		Symmetric diff
	Dictionary
		Get All Keys
		Get Key and Value
		Find Same Keys
		Set a Default Value
		Update Dictionary
		Merge Two Dictionaries
		Emulating a Dictionary
		LRU Cache
	Heap
		Heap Sort
		Priority Queue
	Function
		Document Functions
		Default Arguments
		Option Arguments
		Unpack Arguments
		Keyword-Only Arguments
		Annotations
		Callable
		Get Function Name
		Lambda
		Generator
		Decorator
		Decorator with Arguments
		Cache
	Classes and Objects
		List Attributes
		Get Instance Type
		Declare a Class
		Has / Get / Set Attributes
		Check Inheritance
		Get Class Name
		New and Init
		The Diamond Problem
		Representation of a Class
		Callable Object
		Context Manager
		Using contextlib
		Property
		Computed Attributes
		Descriptor
		Singleton Decorator
		Static and Class Methond
		Abstract Method
		Using slot to Save Memory
		Common Magic
	Generator
		Glossary of Generator
		Produce value via generator
		Unpacking Generators
		Implement Iterable object via generator
		Send message to generator
		yield from expression
		yield (from) EXPR return RES
		Generate sequences
		What RES = yield from EXP actually do?
		for _ in gen() simulate yield from
		Check generator type
		Check Generator State
		Simple compiler
		Context manager and generator
		What @contextmanager actually doing?
		profile code block
		yield from and __iter__
		yield from == await expression
		Closure in Python - using generator
		Implement a simple scheduler
		Simple round-robin with blocking
		simple round-robin with blocking and non-blocking
		Asynchronous Generators
		Asynchronous generators can have try..finally blocks
		send value and throw exception into async generator
		Simple async round-robin
		Async generator get better performance than async iterator
		Asynchronous Comprehensions
	Typing
		Without type check
		With type check
		Basic types
		Functions
		Classes
		Generator
		Asynchronous Generator
		Context Manager
		Asynchronous Context Manager
		Avoid None access
		Positional-only arguments
		Multiple return values
		Union[Any, None] == Optional[Any]
		Be careful of Optional
		Be careful of casting
		Forward references
		Postponed Evaluation of Annotations
		Type alias
		Define a NewType
		Using TypeVar as template
		Using TypeVar and Generic as class template
		Scoping rules for TypeVar
		Restricting to a fixed set of possible types
		TypeVar with an upper bound
		@overload
		Stub Files
	Datetime
		Timestamp
		Date
		Format
		Convert date to datetime
	Files and I/O
		Read a File
		Readline
		Reading File Chunks
		Write a File
		Create a Symbolic Link
		Copy a File
		Move a File
		List a Directory
		Create Directories
		Copy a Directory
		Remove a Directory
		Path Join
		Get Absolute Path
		Get Home Directory
		Get Current Directory
		Get Path Properties
		Read a gzip CSV
		Linux Inotify
	Operating System
		Get Number of CPUs
		Set Affinity
Advanced Cheat Sheet
	Regular Expression
		Compare HTML tags
		re.findall() match string
		Group Comparison
		Non capturing group
		Back Reference
		Named Grouping (?P)
		Substitute String
		Look around
		Match common username or password
		Match hex color value
		Match email
		Match URL
		Match IP address
		Match Mac address
		Lexer
	Socket
		Get Hostname
		Get address family and socket address from string
		Transform Host & Network Endian
		IP dotted-quad string & byte format convert
		Mac address & byte format convert
		Simple TCP Echo Server
		Simple TCP Echo Server through IPv6
		Disable IPv6 Only
		Simple TCP Echo Server Via SocketServer
		Simple TLS/SSL TCP Echo Server
		Set ciphers on TLS/SSL TCP Echo Server
		Simple UDP Echo Server
		Simple UDP Echo Server Via SocketServer
		Simple UDP client - Sender
		Broadcast UDP Packets
		Simple UNIX Domain Socket
		Simple duplex processes communication
		Simple Asynchronous TCP Server - Thread
		Simple Asynchronous TCP Server - select
		Simple Asynchronous TCP Server - poll
		Simple Asynchronous TCP Server - epoll
		Simple Asynchronous TCP Server - kqueue
		High-Level API - selectors
		Simple Non-blocking TLS/SSL socket via selectors
		“socketpair” - Similar to PIPE
		Using sendfile to copy
		Sending a file through sendfile
		Linux kernel Crypto API - AF_ALG
		AES-CBC encrypt/decrypt via AF_ALG
		AES-GCM encrypt/decrypt via AF_ALG
		AES-GCM encrypt/decrypt file with sendfile
		Compare the performance of AF_ALG to cryptography
		Sniffer IP packets
		Sniffer TCP packet
		Sniffer ARP packet
	Asyncio
		asyncio.run
		Future like object
		Future like object __await__ other task
		Patch loop runner _run_once
		Put blocking task into Executor
		Socket with asyncio
		Event Loop with polling
		Transport and Protocol
		Transport and Protocol with SSL
		Asynchronous Iterator
		What is asynchronous iterator
		Asynchronous context manager
		What is asynchronous context manager
		decorator @asynccontextmanager
		Simple asyncio connection pool
		Get domain name
		Gather Results
		Simple asyncio UDP echo server
		Simple asyncio Web server
		Simple HTTPS Web Server
		Simple HTTPS Web server (low-level api)
		TLS Upgrade
		Using sendfile
		Simple asyncio WSGI web server
	Concurrency
		Execute a shell command
		Create a thread via “threading”
		Performance Problem - GIL
		Consumer and Producer
		Thread Pool Template
		Using multiprocessing ThreadPool
		Mutex lock
		Deadlock
		Implement “Monitor”
		Control primitive resources
		Ensure tasks has done
		Thread-safe priority queue
		Multiprocessing
		Custom multiprocessing map
		Graceful way to kill all child processes
		Simple round-robin scheduler
		Scheduler with blocking function
		PoolExecutor
		How to use ThreadPoolExecutor?
		What does “with ThreadPoolExecutor” work?
		Future Object
		Future error handling
	SQLAlchemy
		Set a database URL
		Sqlalchemy Support DBAPI - PEP249
		Transaction and Connect Object
		Metadata - Generating Database Schema
		Inspect - Get Database Information
		Reflection - Loading Table from Existing Database
		Print Create Table Statement with Indexes (SQL DDL)
		Get Table from MetaData
		Create all Tables Store in “MetaData”
		Create Specific Table
		Create table with same columns
		Drop a Table
		Some Table Object Operation
		SQL Expression Language
		insert() - Create an “INSERT” Statement
		select() - Create a “SELECT” Statement
		join() - Joined Two Tables via “JOIN” Statement
		Fastest Bulk Insert in PostgreSQL via “COPY” Statement
		Bulk PostgreSQL Insert and Return Inserted IDs
		Update Multiple Rows
		Delete Rows from Table
		Check Table Existing
		Create multiple tables at once
		Create tables with dynamic columns (Table)
		Object Relational add data
		Object Relational update data
		Object Relational delete row
		Object Relational relationship
		Object Relational self association
		Object Relational basic query
		mapper: Map Table to class
		Get table dynamically
		Object Relational join two tables
		join on relationship and group_by count
		Create tables with dynamic columns (ORM)
		Close database connection
		Cannot use the object after close the session
		Hooks
	Security
		Simple https server
		Generate a SSH key pair
		Get certificate information
		Generate a self-signed certificate
		Prepare a Certificate Signing Request (csr)
		Generate RSA keyfile without passphrase
		Sign a file by a given private key
		Verify a file from a signed digest
		Simple RSA encrypt via pem file
		Simple RSA encrypt via RSA module
		Simple RSA decrypt via pem file
		Simple RSA encrypt with OAEP
		Simple RSA decrypt with OAEP
		Using DSA to proof of identity
		Using AES CBC mode encrypt a file
		Using AES CBC mode decrypt a file
		AES CBC mode encrypt via password (using cryptography)
		AES CBC mode decrypt via password (using cryptography)
		AES CBC mode encrypt via password (using pycrypto)
		AES CBC mode decrypt via password (using pycrytpo)
		Ephemeral Diffie Hellman Key Exchange via cryptography
		Calculate DH shared key manually via cryptography
		Calculate DH shared key from (p, g, pubkey)
	Secure Shell
		Login ssh
	Boto3
	Test
		A simple Python unittest
		Python unittest setup & teardown hierarchy
		Different module of setUp & tearDown hierarchy
		Run tests via unittest.TextTestRunner
		Test raise exception
		Pass arguments into a TestCase
		Group multiple testcases into a suite
		Group multiple tests from different TestCase
		Skip some tests in the TestCase
		Monolithic Test
		Cross-module variables to Test files
		skip setup & teardown when the test is skipped
		Re-using old test code
		Testing your document is right
		Re-using doctest to unittest
		Customize test report
		Mock - using @patch substitute original method
		What with unittest.mock.patch do?
		Mock - substitute open
	C Extensions
		Simple setup.py
		Customize CFLAGS
		Doc String
		Simple C Extension
		Release the GIL
		Acquire the GIL
		Get Reference Count
		Parse Arguments
		Calling Python Functions
		Raise Exception
		Customize Exception
		Iterate a List
		Iterate a Dictionary
		Simple Class
		Simple Class with Members and Methods
		Simplie Class with Getter and Setter
		Inherit from Other Class
		Run a Python Command
		Run a Python File
		Import a Python Module
		Import everything of a Module
		Access Attributes
		Performance of C Extension
		Performance of ctypes
		ctypes Error handling
Appendix
	Why does Decorator Need @wraps
	A Hitchhikers Guide to Asynchronous Programming
		Abstract
		Introduction
		Callback Functions
		Event Loop
		What is a Coroutine?
		Conclusion
		Reference
	Asyncio behind the Scenes
		What is Task?
		How does event loop work?
		How does asyncio.wait work?
		Simple asyncio.run
		How does loop.sock_* work?
		How does loop.create_server work?
	PEP 572 and The Walrus Operator
		Abstract
		Introduction
		Why := ?
		Scopes
		Pitfalls
		Conclusion
		References
	Python Interpreter in GNU Debugger
		Abstract
		Introduction
		Define Commands
		Dump Memory
		Dump JSON
		Highlight Syntax
		Tracepoints
		Profiling
		Pretty Print
		Conclusion
		Reference