Some cool ruby tips and tricks...

ruby_tips.md

Some nice ruby tips and trikcs

Deep dive into ruby scopes

has_secure_token to generate unique random token in Rails 5

Enumerable modules in ruby

Finding positive numbers in an array:

# instead of using sort of a for loop, but we can express the same login using a simple select statement:
2.3.0 :001 > [1,-12,3,-4,-10,2].select {|n| n.positive? }
 => [1, 3, 2]
2.3.0 :002 > # even more shorter
2.3.0 :003 >   [1,-12,3,-4,-10,2].select(&:positive?)
 => [1, 3, 2]

There are generally two ways to call an Enumerable method:

By passing a block like we’ve seen above
By passing a symbol with an & character before it, otherwise known as Symbol#to_proc

In below snippet map method will iterate over some piece of data e.g; an array

names = User.limit(3).map { |user| user.name }
# => ["name1", "name2", "name3"]

Here’s another method that’s included in the `Enumerable` module: `reduce`. In this case:

["First", "Middle", "Last"].reduce { |str, val| "#{str}, #{val}" }
# => "First, Middle, Last"

Make something Enumerable

Now that we’ve taken a look at how to use the methods found within Enumerable

class Array
  include MyEnumerable
end

module MyEnumerable
  def my_reduce(acc, operator = nil, &block)
    raise ArgumentError, 'both operator and actual block given' if operator && block
    raise ArgumentError, 'either operator or block must be given' unless operator || block

    # if no block, create a lambda from the operator (symbol)
    block = block || -> (acc, value) { acc.send(operator, value) }

    each do |value|
      acc = block.call(acc, value)
    end
    acc
  end
end

p [1,2,3,4].my_reduce(0) { |total, num| total + num }
# => 10
p [1,2,3,4].my_reduce(0, :+)
# => 10

reference: blog.codeship.com