Send Basics

Ruby can call a method whose name is stored in a variable.
dynamic call `public_send` calls a public method by name while keeping the example bounded and explicit.
                            method_name
                            method_name = "greet" (default)method_name = "shout"method_name = "label"
                        

                            send_basics.rb
                        
Replay: real traced execution (multi-file project)

                            class Greeter
  def greet
    "hello"
  end

  def shout
    "HELLO"
  end

  def label
    "greeting"
  end
end

method_name = "greet"
greeter = Greeter.new

result = greeter.public_send(method_name)

puts "method=#{method_name}"
puts "result=#{result}"
class Greeter
  def greet
    "hello"
  end

  def shout
    "HELLO"
  end

  def label
    "greeting"
  end
end

method_name = "shout"
greeter = Greeter.new

result = greeter.public_send(method_name)

puts "method=#{method_name}"
puts "result=#{result}"
class Greeter
  def greet
    "hello"
  end

  def shout
    "HELLO"
  end

  def label
    "greeting"
  end
end

method_name = "label"
greeter = Greeter.new

result = greeter.public_send(method_name)

puts "method=#{method_name}"
puts "result=#{result}"

                        
1method_name ← greet, greeter ← ⟨Greeter A⟩⋯15method_name→ greet = "greet"  #@method_name="shout", "label"16greeter→ ⟨Greeter A⟩ = Greeter.new1718result = greeter.public_send(method_name)hello⋯
2result ← hello⋯18result→ hello = greeter.public_send(method_name)hello1920puts "method=#{method_namegreet}"21puts "result=#{resulthello}"⋯outputmethod=greet
result=hello
1method_name ← shout, greeter ← ⟨Greeter A⟩⋯15method_name→ shout = "shout"16greeter→ ⟨Greeter A⟩ = Greeter.new1718result = greeter.public_send(method_name)HELLO⋯
2result ← HELLO⋯18result→ HELLO = greeter.public_send(method_name)HELLO1920puts "method=#{method_nameshout}"21puts "result=#{resultHELLO}"⋯outputmethod=shout
result=HELLO
1method_name ← label, greeter ← ⟨Greeter A⟩⋯15method_name→ label = "label"16greeter→ ⟨Greeter A⟩ = Greeter.new1718result = greeter.public_send(method_name)greeting⋯
2result ← greeting⋯18result→ greeting = greeter.public_send(method_name)greeting1920puts "method=#{method_namelabel}"21puts "result=#{resultgreeting}"⋯outputmethod=label
result=greeting