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Async and Await: Here be dragons

Overview

Background
Basics
Concepts
Examples

In the Beginning …

Code is clean if it can be understood easily – by everyone on the team. Clean code can be read and enhanced by a developer other than its original author. With understandability comes readability, changeability, extensibility and maintainability.

General rules

Follow standard conventions.
Keep it simple stupid. Simpler is always better. Reduce complexity as much as possible.
Boy scout rule. Leave the campground cleaner than you found it.
Always find root cause. Always look for the root cause of a problem.

Design rules

Docker Hub 镜像加速器

国内从 Docker Hub 拉取镜像有时会遇到困难，此时可以配置镜像加速器。Docker 官方和国内很多云服务商都提供了国内加速器服务。

Dockerized 实践 https://github.com/y0ngb1n/dockerized

配置加速地址

Ubuntu 16.04+、Debian 8+、CentOS 7+

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

UPDATE (March 2020, thanks @ic): I don't know the exact AMI version but yum install docker now works on the latest Amazon Linux 2. The instructions below may still be relevant depending on the vintage AMI you are using.

Amazon changed the install in Linux 2. One no-longer using 'yum' See: https://aws.amazon.com/amazon-linux-2/release-notes/

Docker CE Install

sudo amazon-linux-extras install docker
sudo service docker start

UPDATE (March 2020, thanks @ic): I don't know the exact AMI version but yum install docker now works on the latest Amazon Linux 2. The instructions below may still be relevant depending on the vintage AMI you are using.

Amazon changed the install in Linux 2. One no-longer using 'yum' See: https://aws.amazon.com/amazon-linux-2/release-notes/

Docker CE Install

sudo amazon-linux-extras install docker
sudo service docker start


	/**
	* @param {string} rootPath
	* @returns {Generator<string>}
	*/
	function* walk(rootPath) {
	for (const entry of fs.readdirSync(rootPath, { withFileTypes: true })) {
	const filePath = path.join(rootPath, entry.name);
	if (entry.isDirectory()) yield* walk(filePath);
	else yield filePath;

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Alpine.js-TailwindCSS-Lightbox-Modal</title>
	<link href="https://unpkg.com/tailwindcss@^1.0/dist/tailwind.min.css" rel="stylesheet">
	<script src="https://cdn.jsdelivr.net/gh/alpinejs/alpine@v2.x.x/dist/alpine.min.js" defer></script>
	</head>
	<body>

	import numpy as np
	import numpy.linalg

	# Relevant links:
	# - http://stackoverflow.com/a/32244818/263061 (solution with scale)
	# - "Least-Squares Rigid Motion Using SVD" (no scale but easy proofs and explains how weights could be added)


	# Rigidly (+scale) aligns two point clouds with know point-to-point correspondences
	# with least-squares error.