Ruby Class vs Struct

Question

I have seen codebases using Structs to wrap around attributes and behavior inside a class. What is the difference between a Ruby Class and a Struct? And when should one be used over the other.?

Answer 1

From the Struct docs:

A Struct is a convenient way to bundle a number of attributes together, using accessor methods, without having to write an explicit class.

The Struct class generates new subclasses that hold a set of members and their values. For each member a reader and writer method is created similar to Module#attr_accessor.

So, if I want a Person class that I can access a name attribute (read and write), I either do it by declaring a class:

class Person   attr_accessor :name    def initalize(name)     @name = name   end end 

or using Struct:

Person = Struct.new(:name) 

In both cases I can run the following code:

 person = Person.new  person.name = "Name"  #or Person.new("Name")  puts person.name 

When use it?

As the description states we use Structs when we need a group of accessible attributes without having to write an explicit class.

For example I want a point variable to hold X and Y values:

point = Struct.new(:x, :y).new(20,30) point.x #=> 20 

Some more examples:

• http://blog.steveklabnik.com/posts/2012-09-01-random-ruby-tricks--struct-new
• "When to use Struct instead of Hash in Ruby?" also has some very good points (comparing to the use of hash).