dangjlin

-- show tables
\dt

-- create a new database
# CREATE DATABASE mydb;

-- create user

# CREATE USER abhinay with password 'secret';

dangjlin

#source ~/.bashrc
# please manually run source ~/.bashrc to load environmnet variables and path
#type rbenv

git clone https://github.com/rbenv/ruby-build.git ~/.rbenv/plugins/ruby-build

rbenv install 2.3.0
rbenv global 2.3.0
ruby -v

dangjlin

#!/usr/bin/env bash

# usage:  curl -L https://gist.githubusercontent.com/dangjlin/2dd09f80d114e54b54be89ce8b9c6336/raw/b5eb841f9989609c1c6d19c1b47cdca416435509/init_install.sh | sh
# Pre-requisites
sudo apt-get -y update
sudo timedatectl set-timezone Asia/Taipei
sudo apt-get --no-install-recommends -y install git-core zlib1g zlib1g-dev libxml2-dev libxslt-dev libc6-dev ncurses-dev automake libtool subversion pkg-config

#from digital ocean suggestion
sudo apt-get --no-install-recommends -y install autoconf bison build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm3 libgdbm-dev

dangjlin

module ActiveModel
  module Validations
    extend ActiveSupport::Concern
    # ...
    
  module ClassMethods
   def validate(*args, &block) 

# ...

dangjlin

module M2
  extend ActiveSupport::Concern
  
  included do
    my_attr_reader :age
  end
end

module M1
  extend ActiveSupport::Concern

dangjlin

module ActiveSupport
  module Concern
    def append_features(base)
      if base.instance_variable_defined?(:@_dependencies) 
        base.instance_variable_get(:@_dependencies) << self
      return false
      else
      return false if base < self
        @_dependencies.each { |dep| base.send(:include, dep) }
      super

dangjlin

module ActiveSupport
  module Concern
    def append_features(base)
# ...

dangjlin

module M
  def self.append_features(base); end
end

class C 
  include M
end

C.ancestors
# => [C, Object, Kernel, BasicObject]

dangjlin

module ActiveSupport 
  module Concern
  class MultipleIncludedBlocks < StandardError #:nodoc: 
    def initialize
      super "Cannot define multiple 'included' blocks for a Concern" 
    end
  end

  def self.extended(base) base.instance_variable_set(:@_dependencies, [])
  end

dangjlin

require 'active_support' 
module MyConcern
  extend ActiveSupport::Concern
  def an_instance_method; "an instance method"; end

  module ClassMethods
    def a_class_method; "a class method"; end
  end 
end