tsnieman

Advanced memoization and effects in React

Memoization is a somewhat fraught topic in the React world, meaning that it's easy to go wrong with it, for example, by [making memo() do nothing][memo-pitfall] by passing in children to a component. The general advice is to avoid memoization until the profiler tells you to optimize, but not all use cases are general, and even in the general use case you can find tricky nuances.

Discussing this topic requires some groundwork about the technical terms, and I'm placing these in once place so that it's easy to skim and skip over:

• Memoization means caching the output based on the input; in the case of functions, it means caching the return value based on the arguments.
• Values and references are unfortunately overloaded terms that can refer to the low-level implementation details of assignments in a language like C++, for example, or to memory

tsnieman

#!/usr/bin/python
# -*- coding: utf-8 -*- 
'''
This is a little script to download every song from every playlist
if your Google Play Music account. Songs are organized as follows:
    <playlist>/<artist>/<album>/<song>.mp3

I Highly recomend putting this file in your %USER%\Music folder
before running.

tsnieman

sudo apt-get remove --purge vim vim-runtime vim-gnome vim-tiny vim-gui-common
 
sudo apt-get install liblua5.1-dev luajit libluajit-5.1 python-dev ruby-dev libperl-dev libncurses5-dev libatk1.0-dev libx11-dev libxpm-dev libxt-dev

#Optional: so vim can be uninstalled again via `dpkg -r vim`
sudo apt-get install checkinstall

sudo rm -rf /usr/local/share/vim /usr/bin/vim

cd ~

tsnieman

// getComponent is a function that returns a promise for a component
// It will not be called until the first mount
function asyncComponent(getComponent) {
  return class AsyncComponent extends React.Component {
    static Component = null;
    state = { Component: AsyncComponent.Component };

    componentWillMount() {
      if (!this.state.Component) {
        getComponent().then(Component => {