Memoization is an optimization technique that can significantly improve the result of expensive computation by caching the data. This technique works perfectly for Ruby on Rails applications. It includes caching the output of complex computing methods and returning it when the same input is entered again.
The ||= operator is a frequently used technique in Ruby memoization implementation.
Performance optimization is essential for Ruby on Rails applications, particularly when handling costly computations and a high volume of database queries. Memoization is a strategy that, by caching the outcomes of costly operations, can greatly increase performance. Using the ||= operator is one of the easiest ways to do memoization in Ruby.
Example
Let's take an example for calculating the factorial of a number. Factorial is denoted as (!n). It is calculated as the product of all positive integers less than or equal to n.
class Factorial
def calculate(n)
return 1 if n<=1
n * calculate(n - 1)
end
end
fact = Factorial.new
puts fact.calculate(5)
#output = 120
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This is the example for calculating the factorial of a number. In this, each call to the calculation method leads to unnecessary calculation.
Challenges
The primary difficulty in this case is doing the same calculations again, which could cause impactful performance issues for greater values of n.
The solution for the above problem is Memoization with ‘||=’
Memoization is an approach where you actually save the result of a method that is being called repeatedly and then reuse the result of that stored method when that method is called again. The ‘||=’ operator in Ruby provides a simple way to implement memoization.
‘||=’ this operator is shorthand for “or equals”. It assigns a value to a variable only if that variable is nil or false.
Example
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With Memoization
class Factorial
def initialize
@value = {}
end
def calculate(n)
return 1 if n <= 1
if @value[n]
puts "Returning from memoized value for #{n}!"
return @value[n]
end
puts "Calculating factorial for #{n}"
@value[n] ||= n * calculate(n - 1)
end
end
fact = Factorial.new
puts fact.calculate(5)
#output
puts fact.calculate(5)
Calculating factorial for 5
Calculating factorial for 4
Calculating factorial for 3
Calculating factorial for 2
120
puts fact.calculate(7)
Calculating factorial for 7
Calculating factorial for 6
Returning from memoized value for 5!
5040
puts fact.calculate(5)
Returning from memoized value for 5!
120
puts fact.calculate(3)
Returning from memoized value for 3!
6
In this example, the calculate method uses memoization with this ‘||=’ operator. The purpose of this operator is to check if the factorial for the given number is already present or not in the @value hash, if present then returns the prints and return value. If you first calculate 5! Then 7! Then memoization will use 5! Result for calculation, which is more efficient.
The above example prints the result with a memoized value.
Memoization with the ‘||=’ operator is a simple and powerful technique to optimize the performance of your applications. By caching the results of expensive operations, you can significantly reduce the computational overhead and improve the efficiency of your application.
Memoization is an optimization technique that caches expensive computation results, returning stored values for repeated inputs to improve performance.
The ||= operator assigns a value to a variable only if it's nil or false, enabling simple memoization implementation.
Use memoization for frequently called methods with complex computations or database queries that return consistent results for the same inputs.
Backend Developer with 3+years of experience with Ruby on Rails. Specialising in backend optimisation, API development, and database. Enthusiastic about developing scalable, effective solutions.