Evaluates one of several different types of methods within the context of the given object. Methods can be one of the following types:

• Symbol
• Method / Proc
• String

Examples

Below are examples of the various ways that a method can be evaluated on an object:

  class Person
    def initialize(name)
      @name = name
    end

    def name
      @name
    end
  end

  class PersonCallback
    def self.run(person)
      person.name
    end
  end

  person = Person.new('John Smith')

  evaluate_method(person, :name)                            # => "John Smith"
  evaluate_method(person, PersonCallback.method(:run))      # => "John Smith"
  evaluate_method(person, Proc.new {|person| person.name})  # => "John Smith"
  evaluate_method(person, lambda {|person| person.name})    # => "John Smith"
  evaluate_method(person, '@name')                          # => "John Smith"

Additional arguments

Additional arguments can be passed to the methods being evaluated. If the method defines additional arguments other than the object context, then all arguments are required.

For example,

  person = Person.new('John Smith')

  evaluate_method(person, lambda {|person| person.name}, 21)                              # => "John Smith"
  evaluate_method(person, lambda {|person, age| "#{person.name} is #{age}"}, 21)          # => "John Smith is 21"
  evaluate_method(person, lambda {|person, age| "#{person.name} is #{age}"}, 21, 'male')  # => ArgumentError: wrong number of arguments (3 for 2)