Object#send

obj.send(symbol, *args) -> obj

Returns: Object · Updated March 13, 2026 · Core Classes

methods dynamic metaprogramming core-classes

Object#send dynamically invokes a method by name at runtime. The method name can be a Symbol or String, and any additional arguments are passed to that method. This is the foundation of Ruby’s metaprogramming capabilities, enabling you to call methods whose names are determined at runtime rather than compile time.

Syntax

object.send(method_name, *arguments)

Parameters

Parameter	Type	Default	Description
`method_name`	`Symbol` or `String`	—	The name of the method to invoke
`*arguments`	`Object`	`[]`	Arguments to pass to the method

Examples

Basic usage

class Greeter
  def hello(name)
    "Hello, #{name}!"
  end
  
  def goodbye(name)
    "Goodbye, #{name}!"
  end
end

greeter = Greeter.new
greeter.send(:hello, "World")
# => "Hello, World!"

greeter.send("goodbye", "Alice")
# => "Goodbye, Alice!"

Calling private methods

class Secret
  def reveal
    "The password is 12345"
  end
  
  private
  def hidden
    "This is private"
  end
end

secret = Secret.new
secret.send(:hidden)
# => "This is private"

Common Patterns

Dynamic attribute access

class Person
  attr_accessor :name, :age, :email
  
  def initialize(attrs = {})
    attrs.each do |key, value|
      send("#{key}=", value)
    end
  end
end

person = Person.new(name: "Alice", age: 30, email: "alice@example.com")
person.name   # => "Alice"
person.age    # => 30

Building a DSL

class Builder
  def initialize(&block)
    instance_eval(&block) if block_given?
  end
  
  def method_missing(name, *args)
    puts "Building: #{name} with #{args.inspect}"
  end
end

Builder.new do
  create_user name: "Bob", email: "bob@example.com"
  send_email to: "bob@example.com"
end
# Building: create_user with [{:name=>"Bob", :email=>"bob@example.com"}]
# Building: send_email with [{:to=>"bob@example.com"}]

Errors

NoMethodError: Raised if the method does not exist and is not handled by method_missing
ArgumentError: Raised if the wrong number of arguments are passed