Python on VS Code

install python extension

• Press F1, and input "ext install python".
• Then the icon at the leftmost side of the status bar is saying that something is being installed.
• Need to wait a while.
• Use command "ext" + a space to see installed extensions.

use markdown as document

VS Code supports markdown files.
Ctrl+K, V : markdown: Open Preview to the side
Ctrl+Shift+V : markdown: Toggle Preview

create a python project

• Select File -> Open Folder...
• Create a tasks.json file under the .vscode folder in the project folder
• Input below in the task.json file

// A task runner that runs a python program
{
    "version": "0.1.0",
    "command": "python",
    "showOutput": "always",
    "windows": {
        "command": "python.exe"
    },
    "args": ["${file}"]
}

integrate with git

• Make sure you have a repository on the server.
• Install a git tool
• Go to the project directory, open a command window, and run:

# initialize a git repository
git init

# set a remote with name origin
git remote add origin [https://github.com/<username>/<repository>]

# fetch the master branch files from the remote
git pull origin master

• Start VS Code
  • Use the Git panel to work with the remote.

run a python file

• Open the python file.
• Press Ctrl+Shift+B.

debug

• F9 : add/remove a breakpoint.
• F5 or Ctrl + F5 : start debug
• F5 : continue
• F10 : step over
• F11 : step into
• Shift + F11 : step out
• Ctrl + Shift + F10 : restart
• Shift + F5 : stop

print Chinese words, but see question marks in the output console

The issue can be resolved by the following code:

import io
import os
sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf8')

Threading

Please see
http://www.tutorialspoint.com/python/python_multithreading.htm

Example: Execute at most 10 threads in a thread pool

from concurrent.futures import *
...
        with ThreadPoolExecutor(max_workers=10) as executor:
            for url in urls : 
                try:
                    i += 1
                    future = executor.submit(self.get_url, url)
                    future.add_done_callback(threadCallbackHandler(url).handle_callback)
                except Exception as e:
                    print("Failed {0}. {1}".format(url, e))

        # wait all threads finish.         
        executor.shutdown(wait=True)

class threadCallbackHandler:
    def __init__(self, url):
        self.url = url
        
    def handle_callback(self, future) :
        try:
            if (future.exception() != None):
                print("Failed {0}. Exception : {1}".format(self.url, future.exception()))    
        except CancelledError as e:
            print("Cancelled {0}".format(self.url))
        print("Done {0}".format(self.url))