Module: Tins::Responding

Included in:
Object
Defined in:
lib/tins/responding.rb

Overview

A module that provides a convenient way to check if objects respond to specific methods.

The ‘responding?` method returns an object that can be used with the case/when construct to test if an object responds to certain methods. This is particularly useful for duck typing and implementing polymorphic behavior.

end

Examples:

Check duck types

if responding?(:eof?, :gets) === obj
  until obj.eof?
    puts obj.gets
  end

Easy interface checks

case obj
when responding?(:length, :keys)
  puts "  → Hash-like object (has size and keys)"
when responding?(:size, :begin)
  puts "  → Range-like object (has size and begin)"
when responding?(:length, :push)
  puts "  → Array-like object (has size and push)"
when responding?(:length, :upcase)
  puts "  → String-like object (has length and upcase)"
when responding?(:read, :write)
  puts "  → IO-like object (has read and write)"
else
  puts "  → Unknown interface"
end

Instance Method Summary collapse

Instance Method Details

#responding?(*method_names) ⇒ Object

Returns a special object that can be used to test if objects respond to specific methods. The returned object implements ‘===` to perform the check.

This is particularly useful for duck typing and case/when constructs where you want to match against objects based on their interface rather than their class.

Parameters:

  • method_names (Array<Symbol>) —

    One or more method names to check for

Returns:

  • (Object) —

    A special object that responds to ‘===` for method checking



42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
 
# File 'lib/tins/responding.rb', line 42

def responding?(*method_names)
  Class.new do
    define_method(:to_s) do
      "Responding to #{method_names * ', '}"
    end

    alias inspect to_s

    define_method(:===) do |object|
      method_names.all? do |method_name|
        object.respond_to?(method_name)
      end
    end
  end.new
end