The Top Ruby Interview Questions To Prepare For in 2023

Intermediate Ruby interview questions and answers

What is a closure in Ruby and how is it used?

In Ruby, a closure is a group of code that can be run later while keeping the same context it was created in. As a function and its surrounding lexical scope work together, it can remember variables and values even after the outer function is done running.

Closures are often used in situations like callbacks where you want to set up a behavior to be run at a later time but still need to access variables from the scope that set up the behavior.

Explain the concept of procs and lambdas.

Procs and lambdas are objects that encapsulate a block of code for later execution. They are used for defining anonymous functions in Ruby. The main difference between them lies in how they handle return statements and argument checking.

Procs don’t care as much about the number of arguments, but lambdas check all arguments very carefully and act like a normal method. Procs can also change the method or scope around them, but lambdas make sure that return statements inside a block only change that block.

How does Ruby manage memory and garbage collection?

Ruby uses a combination of techniques for memory management and garbage collection. It uses a mark-and-sweep garbage collector to find memory that isn’t being used by the program and get it back. Objects that are no longer reachable through references are considered eligible for garbage collection.

The Ruby interpreter keeps track of object references. When a certain amount of memory is used, the garbage collector is called to get rid of objects that aren’t being used and free up space.

Discuss the super keyword and its usage.

With Ruby’s “super” keyword, you can call a method with the same name in the parent class or module. Its typically used within a subclass to invoke the behavior of the overridden method in the superclass.

When you want to add to or change the functionality of the parent class’s method while still using its core behavior, this is helpful. By calling super from inside the subclass method, you can run the logic of the parent method and then add to it or change it as needed.

What is method_missing and how is it used in Ruby?

In Ruby, the method_missing method is called when an object gets a method call that isn’t defined. This allows you to intercept and handle undefined method calls dynamically.

Its often used to implement custom behavior or to delegate method calls to other objects. By overriding method_missing, you can create powerful dynamic behaviors and metaprogramming constructs within Ruby classes.

Explain multiple inheritance and mixins in Ruby.

Multiple inheritance in Ruby refers to a scenario where a class inherits from more than one parent class. However, Ruby doesnt support multiple-class inheritance directly. Instead, it uses mixins to achieve similar functionality.

Mixins are modules that contain reusable code and can be included in classes. By including a module, a class gains access to its methods and behaviors. This effectively allows a form of multiple inheritance without the complexities and ambiguities associated with traditional multiple inheritance.

Discuss the purpose of the yield keyword in Ruby.

Ruby’s yield keyword is used inside of methods to set up a place to run a block of code that is given when the method is called. It enables you to create methods with flexible behavior. Some of the logic is set up inside the method, and some comes from outside as a block. This is commonly used to implement iterators, callbacks, and custom control structures.

Differentiate between dup and clone methods.

In Ruby, the dup and clone methods are used to make copies of objects, but they do some things differently. When you use the dup method to make a shallow copy of an object, it only copies the instance variables and not the object’s frozen state or singleton methods.

A deeper copy is made by the clone method, which also copies the frozen state and singleton methods. This means that a clone is more thorough in replicating an objects characteristics.

How can you implement custom iterators in Ruby?

In Ruby, you can make your own iterators by declaring a method that takes a block and then using the yield keyword to call the block inside the method. Most of the time, you would use a while, each, or for loop to control the loop and call yield on each item to send it to the block. You can easily go through collections and do custom actions by setting the iteration logic in your method and letting consumers define their behavior through a block.

Describe the role of self in Ruby and its contexts.

In Ruby, the self is a special variable that refers to the current object or instance. Its role can change depending on the context in which its used. Inside an instance method, the self refers to the object on which the method is being called.

In a class method, the self refers to the class itself. To access instance variables, call other methods within the same object, and set class-level behavior, you need to understand and be able to change the self.

Explain the model-view-controller (MVC) architecture in Ruby on Rails.

The model-view-controller (MVC) architecture is a design pattern commonly used in web development, including Ruby on Rails. In this case, the model holds the data and business logic for the application, while the view is in charge of the presentation and user interface. Taking user input, changing data, and controlling the flow are all things that the controller does between the model and the view. This separation of concerns makes applications more maintainable and scalable.

How do you create a new Rails application?

You can use the Rails new command and the name of the application you want to make to make a new Rails application. For example, rails new MyAwesomeApp. When you run this command, a new Rails app is created with a basic directory structure, configuration files, and initial files for setting up the app’s environment. You can also add different settings that let users customize how the app is set up, such as choosing which database to use or skipping over files that aren’t needed.

What is a migration in Ruby on Rails?

A migration in Ruby on Rails is a way to manage changes to the database schema over time. Migrations are Ruby scripts that make it easy to create, modify, and delete database tables, columns, and indexes.

They ensure that database schema evolves as the application grows. They can be versioned, rolled back, and applied consistently. Migrations are an integral part of keeping the database structure in sync with the applications codebase.

Describe the purpose of routes in a Rails application.

Routes in a Rails application define the URLs and their corresponding controller actions. They connect incoming HTTP requests to specific controller methods, which lets you control how your web app navigates and acts.

When you configure routes, you tell the system which endpoints users can access and what they should do when they do so. This centralizes the management of your applications URLs and provides a clear structure for handling different requests.

Explain the concept of associations in ActiveRecord.

In ActiveRecord, associations define the relationships between different models in a Rails application. Associations establish how different records are related to each other in the database. Common types of associations include has_many, belongs_to, has_one, and has_and_belongs_to_many.

It’s easier to query and change related data with these associations. They let you make complex queries and easily manage connections between models.

How can you implement authentication and authorization in a Rails app?

Authentication and authorization can be implemented in a Rails app using gems like Devise or implementing custom solutions. The device provides pre-built authentication features including user registration, login, password recovery, and more.

You can manage authorization with gems like CanCanCan or by setting up access rules by hand based on roles or permissions. These mechanisms ensure that only authorized users can access certain parts of the application and perform specific actions.

Discuss the use of partials and layouts in Rails views.

With Rails’ partials, you can break up complicated views into smaller, easier-to-handle pieces that can be used again and again. By using the same HTML structures in different views, they help you keep your code DRY (don’t repeat yourself).

Layouts, on the other hand, define the overall structure of your applications views including headers, footers, and navigation. Layouts often use partials to make sure that all pages of an application have the same look and feel.

What is caching and how can you implement it in Rails?

Caching is the process of storing frequently accessed data or computed results in memory to improve application performance. Caching can be done at different levels in Rails, such as fragment caching (which saves parts of a view), page caching (which saves whole pages), or even database query caching.

Rails supports caching natively with methods like cache and gives you a choice of cache stores, such as memory stores, file stores, and more advanced ones like Redis.

How do you identify and resolve memory leaks in a Ruby application?

Identifying memory leaks in a Ruby application involves using tools like memory profilers (e. g. , memory_profiler) to track memory usage over time. These tools can help pinpoint code areas that consume excessive memory.

To fix memory leaks, you need to carefully look over your code for places where objects are being held on to when they don’t need to be, make sure garbage collection is working right, and make sure resources are released explicitly. Monitoring memory usage and using good programming practices will aid in preventing memory leaks.

Discuss the global interpreter lock (GIL) and its impact on Rubys performance.

The global interpreter lock (GIL) is a mutex in the CPython interpreter, which is Ruby’s main implementation. It stops multiple native threads from running Python (or Ruby) code at the same time in the same process. This means that even on multi-core systems, only one thread can execute Ruby code at a time. For some types of workloads that involve CPU-bound tasks, GIL can limit the performance gains that could come from using more than one CPU core.

Explain the concept of fibers and their use in managing lightweight concurrent tasks.

Fibers are a simple way to handle multiple tasks at once in Ruby. They let you pause and resume the execution of a block of code. They provide a way to achieve cooperative multitasking where a single thread can manage multiple independent execution contexts.

Fibers are useful for scenarios where you want to perform I/O-bound operations without blocking the entire thread. They provide a level of concurrency without the constraints of the global interpreter lock (GIL).

How can you override a private method in a subclass in Ruby?

In Ruby, private methods cant be directly overridden in subclasses. To get the same result, you can use a protected method in the superclass that the subclass can override. This way, you can give the superclass a common method that can be changed in subclasses because instances of both the superclass and the subclass can access protected methods.

Discuss the differences between eager loading and lazy loading in ActiveRecord.

Eager loading and lazy loading are strategies for fetching associated records in ActiveRecord. Eager loading loads associated records in advance, minimizing the number of database queries and improving performance.

Lazy loading, on the other hand, retrieves associated records only when theyre accessed. This can lead to a higher number of queries but reduces the initial load time. Eager loading is often preferred for optimizing performance, especially when dealing with complex associations.

Explain the role of background jobs and queues in enhancing Ruby application performance.

Background jobs and queues are used to offload time-consuming or non-essential tasks from the main application process. This enhances user experience by reducing response times. You can give tasks like sending emails, processing uploaded files, and doing complicated math to background workers when you use gems like Sidekiq or Resque. This allows your application to remain responsive and scalable even when dealing with resource-intensive tasks.

How can you implement memoization in Ruby to optimize recursive functions?

Memoization is a technique used to optimize recursive functions by caching their results for specific inputs. This prevents redundant calculations for the same input values.

In Ruby, you can implement memoization by:

• Creating a hash to store computed results.
• Checking the hash before performing calculations.
• Storing calculated values for future reference.

This technique is particularly effective for recursive functions with overlapping subproblems.

Describe the purpose of the prepend method in Ruby and how it affects method lookup.

The prepend method in Ruby is used to add a module to the inheritance chain of a class. However, it inserts the module at a higher priority than the class itself. This means that methods in the module that comes before the class take precedence over methods in the class that have the same name.

This is useful for injecting behaviors into a class without completely overriding its existing methods. The prepended modules methods are called before those of the class during method lookup.

What are Ruby refinements and how do they affect method behavior?

Ruby refinements are a feature that lets you change how methods in certain classes or modules work for a short time. Refinements are scoped within a block and affect only the code within that block. They provide a way to “refine” or extend the behavior of classes or modules without permanently altering them. This helps avoid unintended side effects and allows for more controlled and localized changes to method behavior.

Explain the concept of method hooks (method_missing, method_added, method_removed).

Method hooks in Ruby are special methods that get triggered when certain events related to methods occur. method_missing is called when an undefined method is invoked. method_added is called when a new method is added to a class. method_removed is called when a method is removed from a class.

These hooks provide powerful metaprogramming capabilities, allowing you to dynamically respond to or alter method-related events.

How can you create a custom DSL (domain-specific language) in Ruby?

In Ruby, making a custom DSL means defining structures and methods that make the syntax more expressive and easy to read for a certain problem domain. This often includes using blocks or other constructs to encapsulate and configure the behavior.

You can make a DSL that feels like it was made just for one use case by making your API and methods that closely resemble natural language constructs. This makes code more intuitive and maintainable.

Discuss the role of Ruby in creating and manipulating XML and JSON data.

Ruby provides built-in support for creating and manipulating both XML and JSON data. People often use the REXML library to work with XML. It lets you create XML documents, read existing XML, and move around in the XML structure.

There is a module in Ruby called JSON that lets you encode Ruby objects into JSON and decode JSON back into Ruby objects. These capabilities are essential for communication with APIs, data interchange, and web services.

Tired of interviewing candidates to find the best developers?

Hire top vetted developers within 4 days.

Ruby Interview Questions and Answers 2019 Part-2 | Ruby Interview Questions | Wisdom Jobs

FAQ

What kind of questions are asked in 2nd round interview?

Is Ruby good for coding interviews?

What is an important ruby interview question?

This is an important Ruby interview question. Rails Migration can do the following things: 21. Explain the role of sub-directory app/controllers and app/helpers. This is an important Ruby interview question. App/controllers: The Controller handles a user’s web request. Rails look for controller classes in the controller subdirectory.

How to conduct a ruby interview?

Foster a collaborative atmosphere by encouraging the candidate to ask questions during the interview. If you’re employing Ruby in a full-stack capacity, ensure that the candidate possess a fundamental understanding of HTML & CSS. Furthermore, adhering to established interview procedures is crucial when conducting Ruby interviews.

What questions should you ask a ruby student?

Expect to answer questions about what a Ruby program is and how it works, for example. You should commit this explanation to memory so you can rattle it off with a smile when asked about it. Put simply, Ruby is an open-source and general-purpose language with reflective and dynamic qualities.

Why should you ask a ruby engineer a job interview?

These questions also offer hiring managers a methodical framework for objectively and successfully evaluating Ruby engineers. Ultimately, the goal of any job interview is to find the perfect match – a candidate who aligns with the company’s values and has the potential to make a meaningful impact.