Dealing with legacy code that uses different method naming conventions

Working with legacy code often presents unique challenges, especially when dealing with inconsistent method naming conventions. In this article, we'll explore an elegant solution to standardize different method names while maintaining code functionality and readability.

The challenge

Consider a codebase where different service classes use varying method names for their primary actions:

  • Some use validate
  • Others use execute!
  • And some prefer run!

Here's what we're dealing with:

class SpecialServiceValidator
  def self.validate(dates)
    puts 'executing special service validator with validate'
  end
end

class SpecialServiceTwo
  def self.execute!(params)
    puts 'executing special service two with execute!'
  end
end

class SpecialServiceThree
  def self.run!
    puts 'executing special service three with run!'
  end
end

The solution: method objects

Ruby provides a powerful feature through method(:method_name) that allows us to treat methods as first-class objects. This enables us to standardize method calls without changing the original implementation.

Here's how we can implement this approach:

class SampleClass
  def self.call(...)
    new.call(...)
  end

  def initialize(
    special_service_validator: SpecialServiceValidator.method(:validate),
    another_something: SpecialServiceTwo.method(:execute!),
    next_service: SpecialServiceThree.method(:run!)
  )
    @special_service_validator = special_service_validator
    @another_something = another_something
    @next_service = next_service
  end

  def call(params = {})
    special_service_validator.call(params[:some_dates])
    another_something.call(params[:some_other_params])
    next_service.call
  end

  private

  attr_reader :special_service_validator, :another_something, :next_service
end

# then run with:
SampleClass.call
# or
SampleClass.new.call

How it works

  1. We use method(:method_name) to create method objects that wrap the original methods
  2. These method objects are injected through the constructor
  3. All methods can now be called using the standardized .call interface
  4. The original code remains unchanged, maintaining backward compatibility

Why? Benefits...

The implementation of method objects for standardizing legacy code brings multiple valuable advantages to your codebase. Having a consistent interface across different services makes the code more predictable and easier to work with for the entire development team. This approach significantly improves code maintainability as developers can rely on a unified calling convention regardless of the underlying implementation. The combination of these benefits creates a more robust and developer-friendly codebase while respecting the existing architecture and implementation details of legacy systems.

Summary

By leveraging Ruby's method objects, we can create a unified interface for legacy code with different method naming conventions. This approach provides a clean solution without requiring extensive refactoring of existing code.

Happy methoding!