The document discusses how to use delegate in Ruby on Rails to expose contained objects' public methods as your own. It explains that delegate is useful with ActiveRecord associations and uses the syntax "delegate :method_name, to: :target". It also describes how you can delegate to multiple targets, instance variables, class variables, constants, or a class. Additionally, it covers the :allow_nil and :prefix options to delegate, allowing for nil returns or custom prefixes.

1. Delegate
in Ruby on Rails

2. ●
Delegate
●
Options
●
Demo

3. Delegate
●
Easily expose contained objects’ public
methods as your own.
●
Useful with ActiveRecord associations
●
delegate :method_name, to: :target

4. Delegate
●
Multiple delegates to the same target are
allowed
●
delegate :method1, :method2, to: :target
●
Methods can be delegated to instance
variables, class variables, or constants

5. Delegate
●
Delegate a method to the class by using
:class
●
delegate :hello, to: :class

6. Options
●
:allow_nil
●
If the target is nil and does not respond to
the delegated method a NoMethodError is
raised
●
delegate :name, to: :profile, allow_nil: true
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Returns nil

7. Options
●
delegate :name, to: :profile, prefix: true
●
Delegate methods are prefixed with the
name of the object being delegated to.
●
delegate :name, to: :client, prefix: :customer
●
Supply a custom prefix

8. Thank you