# app/models/user.rb
has_one :four_car_garage
has_many :cars
validates :cars, length: { maximum: 4 }

In terminal

vim todo.txt

Colon (:) (lowercase) q vim :q

Just don't use MacVim @joe :D

1. Install latest version of Vim
2. Open a file in Vim
3. ⌘-Q and close the terminal
4. Reopen terminal

This is obviously a joke, it's impossible to quit Vim.

When you want to write destructive migrations please use if_exists: true when you’re trying to remove a table and check for a table existence when you want to add or remove a column ActiveRecord::Base.connection.table_exists?

Case 1:

def up
  drop_table :kittens, if_exists: true
end

Case 2:

def up
  return unless ActiveRecord::Base.connection.table_exists?(:kittens)
  add_column :kittens, :kind, :integer
end

Open term (or equivalent) and paste the following one-liner:

defaults write com.apple.dock persistent-apps -array-add '{tile-data={}; tile-type="spacer-tile";}'; killall Dock

When the Dock restarts, there should be a draggable blank space that you can move anywhere. Repeat to your heart's desire.

Slack allows you to send messages via the Webhooks service

Create a webhook for any channel and then you can send notification using curl.

$ curl -X POST -H 'Content-type: application/json' --data '{"text": "Something important"}'  https://hooks.slack.com/services/YOUR/TOKENIZED/URL

If you want to override previously set order (even through default_scope), use reorder() instead.

E.g.

User.order('id ASC').reorder('name DESC')

would ignore ordering by id completely

Ever wanted to display the structure of the current directory except or two directories?

#NPM or yarn project
tree -I node_modules

# Elixir Mix project
tree -I 'deps|test'

An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once

For example:

• "restful" = "fluster"
• "funeral" = "real fun"
• "adultery" = "true lady"
• "customers" = "store scum"
• "forty five" = "over fifty"

Create a new project using mix new anagram then let's write some test cases:

defmodule AnagramTest do
  use ExUnit.Case

  test "calculates anagram" do
    assert Anagram.anagram?("restful", "fluster") == true
    assert Anagram.anagram?("funeral", "realfun") == true
    assert Anagram.anagram?("adultery", "truelady") == true
    assert Anagram.anagram?("customers", "storescum") == true
    assert Anagram.anagram?("fortyfive", "overfifty") == true
    assert Anagram.anagram?("fiftyfive", "overfifty") == false
    assert Anagram.anagram?("funeral", "real fun") == false
  end
end

Now we have to write the code:

defmodule Anagram do
    def anagram?(a, b) do
    charlist(a) == charlist(b)
  end

  def charlist(w) do
    w |> String.trim() |> String.downcase() |> String.graphemes() |> Enum.sort()
  end
end

Run the tests mix test:

Compiling 1 file (.ex)
Generated anagram app
.

Finished in 0.1 seconds
1 test, 0 failures

Randomized with seed 752850

Done, now you have an anagram calculator!

Simple ones javascript const [a, b, ...c] = [10, 20, 100,200] // a= 10, b=20, c=[100,200] const { first, second } = { first: 1, second: 2 } // first = 1, second = 2

Crazier one javascript const resp = { data: { message: 'hello', random: 'xxx', test:'hehe' } } const { data, data: { message, ...rest } = resp // data = { message: 'hello' }, message = 'hello' // rest = { random: 'xxx', test: 'hehe' }