Hire senior and proven Ruby developers

Created by Yukihiro "Matz" Matsumoto in 1995 in Japan, Ruby is a dynamic programming language focusing on "naturality" and productivity. It is an easy-to-read programming language that tries to mimic the English language as much as possible, allowing the programmer to focus on the problem they are trying to solve and not worry about the intricacies of the programming language. Quoting its creator, Matz, "Ruby is simple in appearance, but is very complex inside, just like our human body."

About Ruby

Ruby is often used in the popular web framework Ruby on Rails. Its readability, rich set of libraries (also called Rubygems), portability, and opinionated configuration make it a popular language (framework) for tech companies who want to build fast and reduce their product's time-to-market. Its underlying principle of convention-over-configuration allows developers to build fast without spending time setting up the right configuration.

Apart from readability, Ruby also provides some advanced features like:

• The mark-and-sweep garbage collector automatically frees up memory occupied by unreferenced variables.
• A SWIG interface that allows you to import Ruby code into your C/C++ source code.
• Elegant support for C extensions will enable you to call Ruby code from C.
• Unified threading interface across all supported platforms, ensuring consistent multi-threading implementation across all supported platforms and environments.

Industries and applications

Ruby and the popular web framework, Ruby on Rails, are widely used in various industries ranging from eCommerce to social networking. It is well-suited for building web applications and backend APIs. Companies like AirBnB, Github, Shopify, Twitch, Kickstarter, etc., have used Ruby on Rails for their platforms.

Due to its underlying principle of convention-over-configuration, Ruby on Rails enables developers to build fast. Hence, it is pretty famous for startups where building fast and receiving customer feedback is crucial.

Must-have technical skills for Ruby developers

Becoming a proficient Ruby developer involves mastering diverse technical skills that form the foundation for creating robust, scalable, and efficient applications. Below are some of the critical skills a Ruby developer must have:

• Ruby syntax and core language concepts: Proficiency in Ruby's syntax and knowledge of core ruby concepts such as modules, classes, lambdas, procs, etc, are basic technical skills required to become a Ruby developer
• Object-Oriented Programming: In Ruby, everything is an object. Every bit of information and code can be given its own properties and actions. So, to become a skilled Ruby developer, one must have a good grasp of object-oriented programming.
• RESTful APIs: Ruby developers are mainly required to work on web applications built using Ruby on Rails or other frameworks such as Hanami, Sinatra, etc. To apply their knowledge of the Ruby language in the real world, they must understand the technology behind web applications and be able to develop RESTful APIs.
• Architectural patterns: Ruby on Rails promotes the MVC framework, and Hanami promotes the Clean Code architectural philosophy. Proficient Ruby developers must be familiar with standard architectural patterns such as MVVM, MVP, MVC, DDD, etc. One need not be familiar with MVC in particular as long as they are familiar with some other pattern since they can easily transfer their existing knowledge of architectural patterns to learn about MVC.
• Database and storage solutions: Real-world applications require developers to work with storage solutions such as PostgreSQL, MongoDB, Redis, etc. Proficient Ruby developers are also expected to be skilled in some of these technologies.
• Security: A developer must be familiar with common security attacks such as SQL injection, Cross-site scripting (XSS), Cross-site request forgery (CSRF), etc., as well as their countermeasures (preferably using Ruby on Rails tools) in order to build a secure web application.

Nice-to-have technical skills

It's crucial to identify candidates who possess core technical competencies and exhibit a willingness to continually enhance their skill set. Below is a range of essential supplementary technical skills that hiring Ruby developers equipped with can bring significant value to your team.

• Test-driven development (TDD): This is a style of development in which the developer first writes the test cases and then implements the business logic to make the tests pass.
• Behaviour-driven development (BDD) is a style of development in which we first define the system's expected behavior from the perspective of the end user and then implement the system.
• Version control: Familiarity with version control tools such as Git is a valuable skill for better collaboration. Besides collaboration, version control also simplifies code management, distribution, debugging, etc.
• Optimization: Knowledge of various optimization techniques, such as eager loading, caching, lazy loading, etc, helps build performant applications.
• Advanced Ruby techniques: Advanced Ruby concepts such as metaprogramming, lambdas, etc., help Ruby developers solve some complex problems elegantly. Frameworks such as Ruby on Rails use these techniques extensively in their source code.
• Deployment: The basic ability to deploy Ruby applications on the cloud and make them available to the world is an invaluable skill.

Interview questions and answers

As you strive to build a top-notch Ruby development team, it's crucial to find candidates who have technical skills and a solid understanding of Ruby's core concepts and best practices. Having a thoughtfully crafted set of interview questions can make the hiring process smoother and help you identify individuals who are well-equipped to contribute to your team's success.

1. How does Ruby manage the memory usage of your program?

Example answer: Ruby uses a mark-and-sweep garbage collection approach to manage memory. This method is responsible for identifying and clearing objects no longer referenced in the program. It automatically frees up memory no longer in use, preventing memory leaks.

2. Explain the concept of "Duck typing".

Example answer: Duck typing is a programming concept where the interface provided by an object is more important than the type of object (class of an object). For example, if an object responds to the upcase method(converts a string to uppercase), it can be treated as a string even if the object is not a string. The principle is often summarised as: If it quacks like a duck, i.e., responds to certain methods, it is treated as a duck.

3. If you wanted to print a custom message whenever an undefined method is called on an object in Ruby, how could you achieve this using metaprogramming techniques?

Example answer: We can override the default behavior for handling undefined methods by defining the method_missing method in the class of the object. With this method, a custom message can be printed. This method will be invoked anytime an undefined method is called. The implementation would look something like this:

class ClassOfObject
def method_missing(method, *args, &block)
puts "Attempted to call undefined method '#{method}'"
end
end

4. What are the advantages of using modules for composition (mixins) over traditional class inheritance? Provide examples to illustrate when using mixins instead of inheritance might be more appropriate.

Example answer: Mixins (using modules in Ruby) allows us to add shared functionality to multiple classes while avoiding the complexities of deep inheritance hierarchies. Inheritance is used when a class is a specific type of another class; for example, Admin being a specific type of User. Whereas, mixins can be used to add abilities to multiple unrelated classes, such as adding logging abilities to unrelated classes like Document and User.

Another example: Both the User and Admin classes may require authentication abilities. This could be handled by adding authentication-related methods directly to the User class, affecting both User and Admin due to the inheritance relationship between the two. Alternatively, this can also be handled by creating an Authenticatable module that includes methods for authentication and "mixin" it in both classes. The approach of creating a module and "mixin" it in the classes helps us adhere closely to the Single Responsibility Principle by keeping the authentication logic out of the User class and also provides more flexibility by allowing us to use this module in any classes that may require it in the future.

5. The following code throws an error. Explain why? How can you fix the error?

class Book
def initialize(title)
@title = title
end
end

b = Book.new("Harry Potter")
puts b.title

Example answer: It should throw a NoMethodError because no method is defined to access the @title instance variable from outside the class Book. In Ruby, instance variables are private, meaning they cannot be accessed directly from outside the class. To fix the error, we can define a getter method that returns the value of the @title instance variable. This can quickly be done using the attr_reader method that automatically defines a getter method of the same name as the name of the instance variable. Here is the fixed code:

class Book
    attr_reader :title

def initialize(title)
@title = title
end
end

b = Book.new("Harry Potter")
puts b.title

6. Are strings mutable in Ruby? How can an object be made immutable in Ruby? What is the benefit of making an object immutable?

Example answer: Yes, strings are mutable in Ruby. The freeze method can be used to make an object immutable. The benefits of making an object immutable are preventing unintended modifications and ensuring object consistency. Unexpected modifications to an object are a significant source of hard-to-debug bugs, especially in concurrent environments. Another benefit of freezing an object is reduced memory usage since it eliminates the need to track modifications to an object.

7. Explain the differences between a lambda and a proc in Ruby. Why might you choose one over the other in different programming scenarios?

Example answer: In Ruby, both lambdas and procs are types of closures, which are essentially blocks of code that can be passed around and executed. They are different in terms of the behavior of the return statement and the way they handle arguments.

Lambdas:

• The return statement returns from the lambda itself, similar to returning from a method.
• Lambdas are strict about the number of arguments they receive. They raise an error if the number of arguments differs from the number of parameters defined.
• In a way, lambdas behave similarly to methods, with the added flexibility of being passed around as variables.
• They are helpful when a function-like behavior is required with the added ability to use the context where the lambda is defined and passed around as a variable.

Procs:

• The return statement exits from the enclosing method where the proc is called.
• A proc cannot be called outside an enclosing method.
• Procs are flexible with handling arguments. They silently ignore any unexpected arguments and assign nil to any missing arguments.
• They work well for callbacks and iterators where the exact number of arguments is unknown or where we want the proc to control the program's flow by breaking out of loops or returning early from a method.

8. What is the Global VM Lock (GVL) in Ruby, and how does it affect the execution of multi-threaded applications?

Example answer: The Global Virtual Machine Lock (GVL) is a mechanism used by the current Ruby VM - YARV that ensures that only one thread executes Ruby code at a time. The purpose of the GVL is to simplify the implementation of the virtual machine and protect the internal data structures of the Ruby environment from race conditions in multi-threaded contexts.

9. When rescuing errors in Ruby, why is it advisable to rescue StandardError instead of Exception?

Example answer: StandardError is a subclass of Exception that includes most of the error types that should be typically handled in an application. These include errors like NoMethodError, TypeError, and others that usually occur due to incorrect method calls or data types.

Rescuing Exception is generally discouraged because it catches every type of exception, including those meant for system-level signals and severe errors such as SignalException, SystemExit, etc.

These exceptions are often intended to terminate the program outright or indicate other serious issues unrelated to the application's business logic.

10. Assume you have many posts in your database, and each post has many comments. How would you efficiently load all the posts and their comments to display on a single page on your Ruby on Rails application?

Example answer: To efficiently load all posts along with their comments in a Ruby on Rails application, it's essential to avoid the N+1 query problem, where each post's comments are loaded in separate database queries. Instead, we can use the includes method provided by ActiveRecord to perform eager loading. This method allows you to load all associated records at the time of the initial query, thus reducing the number of database queries to two: one to fetch all the posts and another to fetch all comments for those posts. The code for loading the posts would look like this:

posts = Post.includes(:comments).all

11. How can you secure your application against SQL injection when running raw SQL queries using ActiveRecord?

Example answer: Raw SQL queries in ActiveRecord can be made safe by parameterization, ensuring that user inputs are correctly escaped. In other words, instead of interpolating variables into the SQL string, bind parameters must be used to pass variables to the raw SQL query. ActiveRecord escapes the provided variables to ensure safe SQL execution. Example:

# Unsafe version (vulnerable to SQL injection)
sql = "SELECT * FROM users WHERE email = '#{params[:email]}'"

# Safe version using bind parameters
sql = "SELECT * FROM users WHERE email = :email"
User.find_by_sql([sql, email: params[:email]]) 

Summary

In conclusion, Ruby stands as a testament to the vision of Yukihiro "Matz" Matsumoto, who introduced it to the world in 1995 with a focus on naturalness and productivity. With its elegant syntax and emphasis on readability, Ruby empowers developers to concentrate on problem-solving rather than wrestling with the complexities of the language itself.

Ruby's versatility shines through its widespread adoption in web development, mainly through frameworks like Ruby on Rails. Its rich set of libraries, convention-over-configuration approach, and portability make it a preferred choice for companies aiming to innovate quickly and bring products to market efficiently.

As you seek to build and strengthen your Ruby development team, it's essential to consider both the must-have and nice-to-have technical skills outlined in this article. By evaluating candidates based on their proficiency in Ruby syntax, object-oriented programming principles, web development expertise, and familiarity with architectural patterns, you can ensure that your team is well-equipped to tackle any challenge that comes their way.

Remember to ask insightful interview questions that delve into candidates' understanding of Ruby's core concepts and their ability to apply them in practical scenarios. This way, you can identify individuals who will contribute significantly to your team's success.

In essence, Ruby's blend of simplicity, elegance, and power makes it a compelling choice for developers and organizations alike, paving the way for innovation and growth in the ever-evolving landscape of software development.