What is the Difference between Ruby Blocks, Procs and Lambdas

Having a problem understanding the difference between ruby blocks, procs and lamdas. What are the blocks? What is the difference between procs and lambdas? Let's break this down.

BLOCKS:

A block is a collection of code enclosed in a do/end statement or between braces { }. They are chunks of code that you can pick up and drop into another method as input or chunk of code that you associate with a method call. If you have used each before to loop through an Enumerable then you have used blocks.

Defining a block

def block_method
  puts "we are in the method"
end

block_method { puts "The block is called"}

PROCS

So what if you want to pass two blocks to your function. How can you save your block into a variable?
Ruby introduces procs so that we are able to pass blocks around. Proc objects are blocks of code that have been bound to a set of local variables.Once bound, the code may be called in different contexts and still access those variables.

Defining procs

You can call new on the Proc class to create a proc . You can use the kernel object proc. Proc method is simply an alias for Proc.new. This can be assigned into a variable.

factor = Proc.new {|n| print n*2 }

or 

factor = proc {|n| print n*2}

//using the proc value

[3,2,1].each(&factor)

>642

LAMBDAS

Can be defined using the method lambda or can be defined as stuby lambda

lamb = lambda {|n| puts 'I am a lambda' }
lamb = -> (n) { puts 'I am a stuby lambda' }

Difference between Procs and Lambdas

Procs don’t care about the correct number of arguments, while lambdas will raise an exception.

Return and break behaves differently in procs and lambdas
Next behaves same way in both procs and lambdas

References

rubyguides.com : Click Here!!!!

I hope that helps someone. Thanks :).

Thanks for reading. 🙂

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