Lucis lucis

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

Git pre-push hook

It will check if current branch is master, then ask a confirmation, in case of master branch

Articles with initial info: https://dev.ghost.org/prevent-master-push/, https://coderwall.com/p/jp7d5q/create-a-global-git-commit-hook

Demo

http://imgur.com/a/EXGAW

	#!/bin/bash

	## Script to merge all mp4 videos in current directory (recursively 2 levels)
	## And update chapter marks to retain the folder/filename

	## Script for merging videos


	filename=`basename pwd`
	current=`pwd`

	/**
	* class for limiting the rate of function calls.
	* Thanks to Pat Migliaccio.
	* see https://medium.com/@pat_migliaccio/rate-limiting-throttling-consecutive-function-calls-with-queues-4c9de7106acc
	* @example let l = new limit(); let logMessageLimited = l.throttleAndQueue(msg => { console.log(msg); }, 500);
	*/
	class limit{
	public callQueue = []

	/**

	states: [
	{ 'AC': 'Acre' },
	{ 'AL': 'Alagoas' },
	{ 'AP': 'Amapá' },
	{ 'AM': 'Amazonas' },
	{ 'BA': 'Bahia' },
	{ 'CE': 'Ceará' },
	{ 'DF': 'Distrito Federal' },
	{ 'ES': 'Espírito Santo' },
	{ 'GO': 'Goías' },

	# use ImageMagick convert
	# the order is important. the density argument applies to input.pdf and resize and rotate to output.pdf
	convert -density 90 input.pdf -rotate 0.5 -attenuate 0.2 +noise Multiplicative -colorspace Gray output.pdf