Ruby Methods: A Comprehensive Guide

Ruby Methods are a fundamental aspect of Ruby programming, acting as reusable blocks of code designed to perform specific tasks. Ruby encapsulates code within methods and enables more precise, organised programming. Methods in Ruby can take parameters and return values and offer flexibility through features like default and variable arguments.   

They are easily invoked by their name, enhancing the readability and maintainability of code. Understanding how to define and use methods is essential for any Ruby programmer, as they play a critical role in structuring code and implementing functionality efficiently and effectively. Read this blog to learn more! 

Table of Contents 

1) What is the Ruby Method? 

2) Return values from Methods 

3) Ruby return Statement 

4) Methods Within Classes 

5) Ruby alias Statement 

6) Ruby undef Statement 

7) Conclusion 

What is the Ruby Method? 

A Ruby Method is a set of expressions that returns a value. In Ruby, methods can bundle one or more repeatable statements into a single unit. Ruby Methods are defined using the ‘def’ keyword and the method name. They can take arguments and return a value. Methods in Ruby are crucial for organising and reusing code, making it more readable and maintainable.  

Ruby Methods can yield blocks, providing a powerful way to abstract functionality and customise behaviour. The last evaluated statement in the method is automatically returned by the method unless an explicit return statement is used. This feature contributes to Ruby's expressive and concise nature. Let’s see how: 

Syntax 

The basic syntax for defining a method in Ruby is:
 

The parentheses can be omitted if the method doesn't take any arguments. Arguments can be defined with default values, and Ruby also supports splat arguments for a variable number of arguments. 

Illustrative example 

Consider a simple method that calculates the sum of two numbers:
 

In this example, ‘sum’ is the method name, and ‘a’ and ‘b’ are parameters. The method adds these two parameters and returns their sum. The ‘puts sum(5, 3)’ line calls the method with arguments 5 and 3 and prints the result, which is 8. This example illustrates the basic structure and usage of a method in Ruby.
 

Return values from Methods 

In Ruby, every method returns a value. The returned value is the result of the last evaluated expression in the method unless an explicit ‘return’ statement is used to specify a different return value. This implicit return feature is a distinctive aspect of Ruby, making the language expressive and concise. 

For example, consider a method that calculates the square of a number:
 

In this method, ‘number * number’ is the last evaluated expression, and its result is automatically returned when the method is called. Therefore, ‘square(4)’ would return 16.  

However, Ruby also allows using the return keyword to specify the return value explicitly. This is particularly useful when you need to return early from a method:
 

In this example, if ‘number’ is zero, the method returns 'Number is zero' immediately. Otherwise, it evaluates the ternary operation and returns 'Positive' or 'Negative' based on the number's value. The explicit ‘return’ is useful for branching and conditional logic within methods. 

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Ruby return Statement 

In Ruby, the ‘return’ statement explicitly specifies the value to be returned by a method. If no ‘return’ statement is used, a Ruby Method automatically returns the value of the last evaluated expression 

Syntax 

In Ruby, the ‘return’ statement exits a method and returns a specific value to the method's caller. The syntax for the return statement is straightforward: ‘return’ followed by the value or expression you want to return. If no value or expression follows ‘return’, the method returns ‘nil’.
 

The ‘return’ keyword is optional when it appears at the end of a method because Ruby implicitly returns the value of the last evaluated expression. 

Illustrative example 

Consider a method that determines the type of a given number:
 

In this example, ‘return’ is used to exit the method immediately with a specific string when a condition is met. The method implicitly returns ' zero ' if none of the conditions are met. 

Methods within classes 

In Ruby, methods are commonly defined within classes. These methods, known as instance methods, are associated with instances of the class. They can access and modify the state of the object to which they belong.  

The ‘def’ keyword is used inside a class definition to define a method within a class. The process can then be called on instances of that class. 

Here's an example:
 

In this example, ‘add’ is an instance method of the ‘Calculator’ class. It adds two numbers and returns the result. An instance of ‘Calculator’ is created, and the ‘add’ method is called on it. 

Ruby alias statement 

In Ruby, the ‘alias’ statement creates a new name or alias for an existing method or global variable, allowing the original name and the alias to be used interchangeably. This feature helps enhance readability or modify behaviour while maintaining compatibility with existing code. 

Syntax 

Ruby's ‘alias’ statement creates an alias for a method or global variable. The syntax is ‘alias new_name old_name’. It allows a method or global variable to be referred to by two names. 

alias new_method_name old_method_name 

Illustrative example
 

In this example, the ‘greet’ method is an alias for the ‘hello’ method in the ‘Greeting’ class. Both ‘g.hello’ and ‘g.greet’ call the same method. 

Ruby undef Statement 

In Ruby, the ‘undef’ statement is used to undefine a method defined in a class, rendering the method inaccessible from instances of that class. This statement is useful for modifying or restricting the interface of a class, especially when subclassing or mixing modules. 

Syntax 

undef method_name 

Illustrative example 

In this example, the ‘farewell’ method is undefined using the ‘undef’ statement. Trying to call ‘farewell’ on an instance of ‘Example’ will result in a ‘NoMethodError’, as the method no longer exists in the class. 

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Conclusion 

Ruby Methods are essential building blocks in Ruby programming, enabling code reusability, organisation, and clarity. They support flexibility through default, variable arguments, block usage, and enhancing code functionality. Mastering Ruby Methods is critical to effective, efficient programming, making them indispensable tools in any Ruby developer's toolkit. 

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