Creating and Invoking a Block in Ruby

Examples of Ruby Block

Let’s see the working of Ruby blocks with the help of code examples.

Example 1:

Creating a block with do-end statements.

["DBMS", "OS", "CN","OOPS", "Algorithms", "Data Structures"].each do |subjects|
puts subjects
end

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Output:

Example 2:

Creating an Inline block or block using curly braces {}.

["DBMS", "OS", "CN","OOPS", "Algorithms", "Data Structures"].each {|subjects| puts subjects}

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Output:

Example 3:

Creating a block where we pass an argument to a Block.

subjects = ["DBMS", "OS", "CN","OOPS", "Algorithms", "Data Structures"]

subjects.each {|subjects| puts subjects}

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Output:

Example 4:

Creating a block where some logic is passed in the argument.

nums = [10,15,20,25,30,35,40,45,50]

puts nums.select { |number| number.even?}

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Output:

We have passed a logic on the list to select only even numbers from the list. We can see we are getting only even numbers from the list as our output.

Working of Yield Statement

A block inside a method is called using the yield keyword and a value in the yield statement.

Let’s see the working of the yield statement with the help of a code example.

# Ruby program to show the working yield statement

# method
def ninjas

# method statement to be executed
puts "Ninjas are Coders!"

# using yield statement
yield

# method statement to be executed
puts "Ninjas are Developers!"

# using yield statement
yield

end

# block
ninjas{puts "Ninjas are Data Scientists!"}

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Output:

In the above program, the method name is ninjas. Method statements are initially invoked, demonstrating that Ninjas are Coders!. However, as soon as yield statements are executed, control is transferred to the block, which then executes its own statements, demonstrating that Ninjas are Data Scientists!. When the Block completes, it returns control to the method, which then continues to run from where the yield statement was invoked. 

Frequently Asked Questions

What are Objects in Ruby?

In Ruby, everything is an object. All objects have a unique identification; they can also maintain a state and exhibit behavior in response to messages. Usually, these messages are sent out via method calls. A string is an example of a Ruby object.

What is a block in Ruby?

In Ruby, a block is similar to a method. Ruby blocks enable us to execute any calculations and manipulation in the same manner as we would inside of any method. Therefore, we can say that while blocks in Ruby are identical to any method, they do not belong to any objects.

What are the main types of blocks in Ruby?

There are mainly three types of blocks in Ruby:-

1.) do and end statement blocks.

2.) Inline blocks or with Curly braces.

3.) Block with arguments.

What is a Global Variable in Ruby?

The variable with global scope which can be accessed from anywhere in the program is known as Global Variable.

What are Global Functions in Ruby?

Kernel-specified methods and any methods defined at the top-level, outside of any classes, are Global Functions. Global functions are defined as private methods of the Object class.

Conclusion

In this article, we have extensively discussed Blocks in Ruby and how to create and invoke the blocks in Ruby with the help of code examples.

If you want to learn more, check out our articles on Object Marshalling in Ruby, Tainting Objects in Ruby, Copying Objects In Ruby, How To Invoke Global Functions In Ruby?, and Object References in Ruby.
Check out this problem - Redundant Braces

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Happy Coding!