In Ruby, How to know if a method is available to an object?

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In Ruby, How to know if a method is available to an object?

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In today's discussion, we'll explore the process of determining whether a specific method is available to an object in Ruby. Ruby provides multiple pathways to achieve the same result, and often the chosen method comes down to personal preference.


Let me guide you through 3 possible solutions.

Diversity in approaches is a characteristic feature of Ruby, setting it apart from some other programming languages where a more standardized approach might be prevalent. For newcomers, this flexibility might seem a bit unfamiliar.

In Ruby, there are often a bunch of different ways to get the same results. Sometimes, the chosen method or solution is just a matter of preference.

The class.methods method




  • parameter: The value for which we want to check available methods.


  • class.methods: Retrieves a list of all methods available to the class of the given parameter.


  • It returns an array containing all the methods available to the class of the specified parameter.

Explanation: The class method alone provides us with the class of the given value. By appending .methods, we can obtain a comprehensive list of all methods associated with that class.

Let's take a look:

# Example 1: Checking methods for an integer
puts 42.class.methods

# Example 2: Checking methods for a string
puts "Hello, Ruby!".class.methods

# Example 3: Checking methods for an array
puts [1, 2, 3].class.methods

Pros and cons

This approach comes with the drawback of potential information overload due to the extensive list of methods, making it challenging to identify the desired method quickly.

Furthermore, the lack of contextual information about each method and the inclusion of potentially deprecated ones can impede developers, necessitating additional resources such as documentation for a more nuanced understanding.

The effectiveness of this approach depends on the developer's familiarity with the class, the specific task, and the need for a broad or precise examination of available methods.

begin/rescue block

Another approach involves using a begin and rescue block to handle the scenario where the method is not present.

This method is less common and might be considered more idiomatic in specific contexts.

  puts "The object has the desired method!"
rescue NoMethodError
  puts "The object does not have the desired method."

PRos and cons

The begin/rescue block approach for checking method availability in Ruby provides explicit and customizable error handling, allowing developers to gracefully manage scenarios where a method is not present.

This approach communicates intent clearly and permits tailored responses to the absence of the desired method. However, it introduces potential performance overhead, especially in situations where the lack of the method is a common occurrence.

Additionally, it may be perceived as less idiomatic within the Ruby community, and the broad rescue block has the potential to inadvertently mask other unrelated errors, necessitating careful consideration of error-handling strategies.

The choice to employ this approach depends on the specific context, emphasizing a trade-off between readability and potential performance implications.

Respond_to method




  • parameter: The value for which we want to check method availability.

  • "method": The name of the method to be checked.


  • respond_to?: Determines if a specific object can respond to a given method.


  • It returns a boolean value (true or false), indicating whether the object can respond to the specified method.

Explanation: The respond_to? method is a concise and efficient way to check if a particular object can respond to a specific method. It returns true if the object has the specified method and false otherwise. This approach is particularly useful when you need a straightforward answer without exploring the entire list of available methods.

Examples with a True Return:

# Example 1: Checking if an array can respond to the 'push' method
array = [1, 3, 5, 0]
puts array.respond_to?("push")  # => true

# Example 2: Checking if a float can respond to the 'round' method
puts (2.4).respond_to?("round")  # => true

Examples with a False Return:

rubyCopy code# Example 3: Checking if a string can respond to the 'sqrt' method
str = "alexandre-calaca"
puts str.respond_to?("sqrt")  # => false

# Example 4: Checking if an integer can respond to the 'substring' method
puts 2.respond_to?("substring")  # => false

Pros and Cons:


  1. Quick Method Verification:

    • Pro: This approach provides a rapid and focused check, returning a boolean value to indicate whether the specified method is available to the object.


  1. Single Method Check:

    • Con: The respond_to? method allows checking for only one method at a time. If you need to verify the availability of multiple methods, individual checks are required.



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Final thoughts

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