Class: LiveCable::Delegator

Inherits:
SimpleDelegator
  • Object
show all
Includes:
ObserverTracking
Defined in:
lib/live_cable/delegator.rb

Overview

Wraps mutable objects (Arrays, Hashes, Models) to track changes.

The Delegator uses Ruby's SimpleDelegator to transparently wrap objects and intercept method calls. When mutative methods are called, observers are notified so the component can be re-rendered.

Architecture:

  • Delegator extends SimpleDelegator to wrap the target object
  • Dynamically extends with type-specific delegation modules (Array/Hash/Model)
  • Each delegation module decorates mutative methods to notify observers
  • Getter methods are not decorated (no notification on read)
  • Nested structures automatically get wrapped in new Delegators with the same observers

Supported Types:

  • Array: Tracks push, <<, delete, etc.
  • Hash: Tracks []=, delete, merge!, etc.
  • ActiveRecord::Base: Tracks assign_attributes, update, etc.

Examples:

Automatic wrapping

container[:tags] = ['ruby', 'rails']
# Container automatically wraps the array in a Delegator
container[:tags] << 'rspec'  # Triggers observer notification

Manual creation

delegator = Delegator.new(['ruby', 'rails'])
delegator.add_live_cable_observer(observer, :tags)
delegator << 'rspec'  # Notifies observer

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ObserverTracking

#add_live_cable_observer, #initialize_clone, #initialize_dup, #remove_live_cable_observer

Constructor Details

#initialize(value) ⇒ Delegator

Returns a new instance of Delegator.

Parameters:

  • value (Object) —

    The object to wrap and track



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# File 'lib/live_cable/delegator.rb', line 48

def initialize(value)
  super

  # Extend with the appropriate delegation module based on value's type
  Delegation::SUPPORTED.each do |klass, delegator|
    if value.is_a?(klass)
      extend delegator
    end
  end
end

Class Method Details

.create_if_supported(value, variable, observer) ⇒ Delegator, Object

Factory method to create a Delegator only if the value's type is supported. Returns the original value unchanged if not supported.

Parameters:

  • value (Object) —

    The value to potentially wrap

  • variable (Symbol) —

    The reactive variable name

  • observer (Observer) —

    The observer to attach

Returns:

  • (Delegator, Object) —

    Wrapped value or original value



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# File 'lib/live_cable/delegator.rb', line 66

def self.create_if_supported(value, variable, observer)
  if supported?(value)
    return new(value).tap do |delegator|
      delegator.add_live_cable_observer(observer, variable)
    end
  end

  value
end

.supported?(value) ⇒ Boolean

Check if a value's type can be wrapped in a Delegator.

Parameters:

  • value (Object) —

    The value to check

Returns:

  • (Boolean) —

    true if value can be delegated



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# File 'lib/live_cable/delegator.rb', line 80

def self.supported?(value)
  Delegation::SUPPORTED.keys.any? { |c| value.is_a?(c) }
end