Simple Ruby 'Or' Question

Simple Ruby 'or' question

["hello", "goodbye"].include? @user.user_type

Simple ruby syntax question

Here is the exact code that you are using under the hood:

https://github.com/marcel/aws-s3/blob/master/lib/aws/s3/bucket.rb

As you can see, there are nested modules/classes:

module AWS
  module S3
     class Bucket < Base
     end
  end
end

So:

• AWS is a module.
• S3 is a module.
• Bucket is a class.

The class Bucket is nested inside the module S3 which is nested inside the module AWS.

A Module is basically a bundle of methods/constants, but they differ from classes in the sense where they can't have instances. You use that a lot in order to refactor your code and to better design it. More information on Modules here.

The :: is used to refer to the nested modules/classes. It's a kind of resolution operator, that helps you reach your nested modules/classes/constants by knowing their paths.

Basic ruby question: the { } vs do/end construct for blocks

In the "not working" case, the block is actually attached to the puts call, not to the collect call. {} binds more tightly than do.

The explicit brackets below demonstrate the difference in the way Ruby interprets the above statements:

puts(test = [1, 1, 1].collect) do |te|
    te + 10
end

puts test = ([1, 1, 1].collect {|te|
    te + 10
})

Ruby question mark operator, what does this mean?

1. (true ? rand(13) : 0) mean (if true then rand(13) else 0 end)

if you have directly "true" in condition, the "else" is never called (is useless), you can write : a = 1 + rand(13) directly ;)

2. rand(13) give random int between 0 and 12 ;)
   if you want "13" put rand(14)
   personally I always use range like this (all range is include, it's easier to understand) : rand(0..13)

Newbie Ruby question - project basic calculator

Use if statement with elsif and else.

math = gets.chomp.downcase 
if math == "add"
    puts user + user2
elsif math == "subtract"
    puts user - user2
elsif math == "multiply"
    puts user * user2
else
    puts "I don't understand"
end

case is also nice for this usecase.

math = gets.chomp.downcase 
case math
when "add"
    puts user + user2
when "subtract"
    puts user - user2
when "multiply"
    puts user * user2
else
    puts "I don't understand"
end

Ruby and Rails Simple Question on Expression

In Ruby, if a variable does not have a value, it is nil by default. To answer your second question, you can use the send method to call your "type" methods. Something like,

def get_profession(type)
  # Making sure correct type is passed.
  raise RuntimeError unless ['first', 'second', 'third'].include?(type.to_s)
  send(type)
end

Send expects a method in a string as parameter, which it calls on the same object. In your case if the response of your "type" method has no value, it would be by default be nil.

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