Class: ShopifyCLI::LazyDelegator

Inherits:
SimpleDelegator
  • Object
show all
Defined in:
lib/shopify_cli/lazy_delegator.rb

Overview

‘LazyDelegator` defers initialization of its underlying delegatee until the latter is accessed for the first time due to a method call that the delegator cannot handle itself:

result = LazyDelegator.new do
  # carry out costly operation ...
end

result      # referencing the object itself does not result in Proc evaluation
result.to_h # however, calling a method on it will result in Proc evaluation

LazyDelegator lends itself to being subclassed in scenarios where some facts are known and others are costly to compute:

class LazySpecificationHandler < ShopifyCLI::LazyDelegator
  attr_reader :identifier

  def initialize(identifier, &initializer)
    super(&initializer)
    @identifier = identifier
  end
end

handler = LazySpecificationHandler.new(:product_subscription) do
   # fetch specification from the Partners Dashboard API ...
end

# Accessing identifier will not result in Proc evaluation as it is
# available as an attribute of the delegator itself
handler.identifier # => :product_subscription

# Accessing the specification will result in evaluation of the Proc
# and in our example in a subsequent network call
handler.specification # => <Extension::Models::Specifcation:...>

Instance Method Summary collapse

Constructor Details

#initialize(&delegatee_initializer) ⇒ LazyDelegator

Returns a new instance of LazyDelegator.



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# File 'lib/shopify_cli/lazy_delegator.rb', line 41

def initialize(&delegatee_initializer)
  super([false, delegatee_initializer])
end