Arup Rakshit aruprakshit

Array Iteration

https://gist.github.com/ljharb/58faf1cfcb4e6808f74aae4ef7944cff

While attempting to explain JavaScript's reduce method on arrays, conceptually, I came up with the following - hopefully it's helpful; happy to tweak it if anyone has suggestions.

Intro

JavaScript Arrays have lots of built in methods on their prototype. Some of them mutate - ie, they change the underlying array in-place. Luckily, most of them do not - they instead return an entirely distinct array. Since arrays are conceptually a contiguous list of items, it helps code clarity and maintainability a lot to be able to operate on them in a "functional" way. (I'll also insist on referring to an array as a "list" - although in some languages, List is a native data type, in JS and this post, I'm referring to the concept. Everywhere I use the word "list" you can assume I'm talking about a JS Array) This means, to perform a single operation on the list as a whole ("atomically"), and to return a new list - thus making it mu

Optimistic Locking assumes that a database transaction conflict is very rare to happen. It uses a version number of the record to track the changes. It raise an error when other user tries to update the record while it is lock.

usage

Just add a lock_version column to the table you want to place the lock and Rails will automatically check this column before updating the record.

Pessimistic locking assumes that database transaction conflict is very likely to happen. It locks the record until the transaction is done. If the record is currently lock and the other user make a transaction, that second transaction will wait until the lock in first transaction is release.

usage

Redux Selector Pattern

Imagine we have a reducer to control a list of items:

function listOfItems(state: Array<Object> = [], action: Object = {}): Array<Object> {
  switch(action.type) {
    case 'SHOW_ALL_ITEMS':
      return action.data.items
    default:

Should be work with 0.18

Destructuring(or pattern matching) is a way used to extract data from a data structure(tuple, list, record) that mirros the construction. Compare to other languages, Elm support much less destructuring but let's see what it got !

Tuple

myTuple = ("A", "B", "C")
myNestedTuple = ("A", "B", "C", ("X", "Y", "Z"))

Proxy cache passes GET instead of HEAD to upstream... so we have a 403.

This version include these fixes.

Remove $request_method from $string_to_sign and pass static string "GET" instead
Remove proxy_buffering directive for allowing the nginx cache

Keyboard shorcuts

CTRL + SHIFT + p: Command panel
CTRL + p: File search
CTRL + r: Method search inside current file
CTRL + g: Go to line #
CTRL + SHIFT + [: Fold code
CTRL + SHIFT + ]: Unfold code
ALT + SHIFT + 2: Double column/file mode
ALT + SHIFT + 1: Single column/file mode

	# In app/helpers/users_helper.rb

	require_relative 'users_helper/greet'

	module UsersHelper
	module Internals
	end
	private_constant :Internals
	include Internals

	class Wrong
	def method_missing(m, *)
	if m =~ /\Ahello_(.+)\z/
	puts "Hello, #{$1.capitalize}"
	else
	super
	end
	end
	end

	original_solution.files.each do \|original_file\|
	f = original_file.dup
	f.remote_name_url = original_file.name.url
	new_solution.files << f
	end

	// Sublime Text - Build System for Javascript
	{
	"cmd": ["node", "$file"],
	"selector": "source.js"
	}