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Table of contents
1.
Introduction
2.
Instance Method
3.
Symbol Class
4.
Symbol Table
5.
Frequently Asked Questions
5.1.
Which should you use, a variable or a symbol, as a rule of thumb?
5.2.
What is a Ruby Symbol?
5.3.
Why should you use symbols instead of strings?
5.4.
In rails, what is a symbol?
5.5.
What do you mean by the Symbol in Ruby?
6.
Conclusion
Last Updated: Mar 27, 2024

Symbols in ruby

Author Kanak Rana
1 upvote
Master Python: Predicting weather forecasts
Speaker
Ashwin Goyal
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Introduction

Symbols in Ruby are a name's internal representation. The Symbol for a name is created by placing a colon(:)  before the name. Regardless of how a given name is used within the program, it will always generate the same symbol by adding “:” before the name. 

Symbol, it looks like a variable name, but a colon initiates it (:), as-.

:symbol

:in

:ruby

:codingNinjas


The symbol is the most basic Ruby object. It's nothing more than a name, and an internal ID. 

Symbols are more valuable and efficient than strings because they refer to the same object throughout a Ruby program. 

Two strings with the same contents are two different objects, but there is only one Symbol object for any given name. It can help you save time and remember things better.

A colon followed by a name creates a Symbol object that matches the identifier. It will make the same object for a given title or string throughout a program's execution. 

Instance Method

  • to_sym->sym

To_sym returns the Symbol that corresponds to an object in general. In this case, the self is returned because sym is already a symbol.

# Ruby program to illustrate the use of to_s method

p :codingninjas.to_s

p :"welcome to codingNinjas portal, Happy coding".to_s

 # .to_s, Returns the name or string corresponding to sym.


Output:

"codingninjas"

"welcome to codingNinjas portal, Happy coding"

  • intern-> sym

To_sym returns the Symbol that corresponds to an object in general. In this case, because sym is already a symbol, self is born.

We can use Symbols objects to represent methods, variables, and other identifiers. Some methods require a symbol, such as defining a method, method missing, and trace var. A string can also be passed to other methods, such as attr accessor, send, or autoloaded.

Symbols are frequently used as hash keys because they are only created once. A new object is created every time a string hash key is used, resulting in some memory overhead. For symbol hash keys, there is even a special Syntax:

name_1 = { :name => "rohit", :age => 32 }

name_2 = { name: "mohit", age: 12 }       


Output:

{"name"=>"mohit", "age"=>12}

"Use a String if the object's textual content is important. Use a Symbol if the object's identity is essential."

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Symbol Class

The Ruby Core Library includes this Symbol class. The general public cannot be created this class. When a new symbol is declared, a Symbol object is implicitly created. The Symbol class is descended from the Object class, the default parent class. It's worth noting that it also includes the Comparable module. The String and Numeric classes have the same ancestor chain as this class.

# Ruby program to show Symbol objects
  
# factor 3
module Coding_ninjas1
class Min
# Ruby program to show Symbol objects
# factor 2
module Coding_ninjas1
class Min
end
$x1 = :Min
end
# factor 1
module Coding_ninjas2
Max = 1
$x2 = :Min
end  
# factor 2
def Min()
end
$x3 = :Min 
puts $x1.object_id 
puts $x2.object_id 
puts $x3.object_id 


Output:

1023268

1023268

1023268


Explanation: If Min is a constant in factor1, a method in factor2, or a class in the factor3, then this:Min will be the same object in all given factors. Basically, the factor is the common name for the classes, method, and constant in the program.

Symbol Table

Ruby keeps track of symbols in a symbol table. Symbols represent names of instance variables, methods, and classes. If a method is called update_blog, a symbol: update blog is created automatically. Ruby always keeps its symbol table on hand, so calling Symbol.all_symbols at any time will tell you what's on it.

An operator, string, variable, constant, method, or class name is prefixed with a colon to create a Symbol object (:). For the duration of a program's execution, the symbol object will be unique for each different name, but it will not refer to a specific instance of the name.

As a result, while Sym can be a constant in one context and a method or a class in another, the Symbol:Sym object will be the same in all three.

Frequently Asked Questions

Which should you use, a variable or a symbol, as a rule of thumb?

We use a string if the object's contents (the sequence of characters) are essential.

We use a symbol when the object's identity is critical.

What is a Ruby Symbol?

A symbol is a one-of-a-kind instance of the Symbol class that is used to identify a particular resource. Examples of resources are

  • a variable 
  • a method
  • a hash key,
  • a state, and so on.
     

Only 1 instance of the Symbol class can be created for each Symbol in a running program, and each Symbol is unique.

Why should you use symbols instead of strings?

Since mutable objects can cause bugs that are difficult to detect, symbols' immutability makes them extremely useful in programming. Because symbols do not change, using them helps to avoid this problem.

Strings can be changed. Symbols cannot".

In rails, what is a symbol?

The “:” (colon) Symbol is an efficient way of representing names and strings; they are literal values, as you mentioned. It is created and only exists once during a Ruby session. It's a symbol, not a string because you don't have access to String methods. Moreover, it is immutable.

What do you mean by the Symbol in Ruby?

The most basic Ruby object we can make is a symbol. It's nothing more than a name and an internal ID. Symbols are more useful and efficient than strings because they refer to the same object throughout a Ruby program.

Conclusion

This blog covered Symbols in Ruby. The difference between strings and symbols in ruby, symbol class, and symbol tables was also covered.
If you want to learn more, check out our articles on Ruby vs. Python: What are the differences, and how do they matter to you?Ruby and Ruby on Rails: How do they differ? and 8 reasons why Ruby should be your first language! and check out our other Ruby articles here and Ruby Documentation 

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