Ruby: Symbol Class

What are Symbols in Ruby?

Ruby symbols are very similar to strings with some key differences. One of the differences is that symbols are immutable in Ruby, i.e., their value cannot be changed once they have been created. Symbols in Ruby are often used as hash keys, method names, and other identifiers. It is represented with a colon sign : before its name.

Let us look at an example of a symbol in Ruby:

This symbol can be represented as a string "example_symbol". However, it is important to note here that symbols are not the same as strings, because it's immutable but strings are mutable. Hence symbols are used differently to increase performance and reduce memory usage.

How to do Ruby Symbols Work?

Ruby symbols behave differently from strings. Ruby allocates memory space and assigns a new object whenever a new string is created. It does not check if the string is a copy of an already existing string or not. If we have two strings with the same value, Ruby will allocate separate memory for each of them and create separate objects to represent them.

On the other hand, when a symbol is created, Ruby first checks if a symbol with the same name already exists or not. If it exists, Ruby doesn't allocate separate memory for the new object. Instead, it returns a reference to the already existing symbol. If the symbol, does not already exist, then Ruby allocates separate memory space and creates the new symbol. This process of checking for existing symbols is much faster and more efficient than creating new objects for strings.

Here is an example to demonstrate the difference between symbols and strings in Ruby:

In this example, two strings with the same value and two symbols with the same name are both created. On comparing their object IDs, we can notice that both the strings have different object IDs whereas the symbols share the same object ID.

Why use a Symbol Instead of Using a String?

There are several reasons why you might choose to use a `symbol instead of a string in Ruby:

Immutability of Symbols

As we have already mentioned, Ruby symbols are immutable. This implies that a symbol cannot be changed once it has been created. Unlike strings, which can be altered using a variety of string methods, symbols cannot be changed once created.

The immutability of Ruby symbols makes them useful for many things like hash keys and other identifiers, where we want to ensure that the value does not change. Additionally, it means that symbols can be securely used throughout our program without having to think about some unexpected changes.

Better Performance by Using Symbols

Using Ruby symbols instead of strings can provide better performance in our program. This is because Ruby checks` for existing symbols before creating new ones, whereas each new string takes up additional memory. This saves up memory space since the same objects are reused multiple times.

Further, Ruby also used symbols in method names. This is because symbols perform quicker and require less memory than strings. This difference can make a huge impact on the performance of our program.

When to Use a Symbol?

Symbols are used in many cases in Ruby. They are used as keys in hashes because of their immutable nature. They are also used as method names. Let us take a look at some of the use cases of symbols in Ruby:

Hash keys

Symbols are often used as keys in hashes. This is because symbols are immutable, so we can be sure that the key will never change. Additionally, using symbols as hash keys can improve the performance of the program as symbols are faster than strings.

Method names

Symbols are often used as method names in Ruby. This is because symbols are faster and use less memory than strings when used as method names. Also, using symbols as method names can make the code easier to read and understand.

Ruby Symbol Class

In Ruby, symbols are represented by the symbol class. The symbol class is a built-in class in Ruby that provides methods for working with symbols. Let us look at some common methods of the symbol class:

to_s

This method converts a symbol to a string.

inspect

This method returns a string representation of the symbol.

==:

This method compares two symbols and returns true if they are equal.

How to Create an Array of Symbols in Ruby?

The way to create an array of symbols in Ruby is very simple. We can use the symbol class to individually create each symbol and then finally add them to an array. For example:

In this example, we create an array of symbols arr with the names :symbol1, :symbol2, and :symbol3.

Ruby Symbol GC Advanced

The memory space that is no longer needed by our program is freed up by the garbage collection (GC) in Ruby. It helps to prevent memory leaks and crashes that may have happened if the memory was not managed properly. It is a complex process but there are some efficient methods used to implement this. One such method is Symbol GC in Ruby. It is a special feature that helps to reduce memory usage by automatically garbage-collecting symbols that are no longer being used.

How to Convert Symbol to String in Ruby?

In Ruby, we have the to_s method that converts any symbol to a string. For example: