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Class: ActiveSupport::Dependencies::WatchStack

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain:
self, ::Enumerable
Inherits: Object
Defined in: activesupport/lib/active_support/dependencies.rb

Overview

The WatchStack keeps a stack of the modules being watched as files are loaded. If a file in the process of being loaded (parent.rb) triggers the load of another file (child.rb) the stack will ensure that child.rb handles the new constants.

If child.rb is being autoloaded, its constants will be added to autoloaded_constants. If it was being required, they will be discarded.

This is handled by walking back up the watch stack and adding the constants found by child.rb to the list of original constants in parent.rb.

Class Method Summary

Instance Attribute Summary

::Enumerable - Included

#many?

Returns true if the enumerable has more than 1 element.

Instance Method Summary

::Enumerable - Included

#exclude?

The negative of the Enumerable#include?.
#index_by

Convert an enumerable to a hash.
#pluck

Convert an enumerable to an array based on the given key.
#sum

Calculates a sum from the elements.
#without

Returns a copy of the enumerable without the specified elements.

Constructor Details

.new ⇒ WatchStack

[ GitHub ] 

  


# File 'activesupport/lib/active_support/dependencies.rb', line 102



def initialize
  @watching = []
  @stack = Hash.new { |h, k| h[k] = [] }
end


  







Instance Attribute Details



  

    #watching   (readonly)
  



  

    

if parent.rb is autoloaded, the stack will look like [[Object]]. If parent.rb then requires namespace/child.rb, the stack will look like [[Object], [Namespace]].


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/dependencies.rb', line 100



attr_reader :watching


  








  

    #watching?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/dependencies.rb', line 111



def watching?
  !@watching.empty?
end


  







Instance Method Details



  

    #each(&block)  
  

  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/dependencies.rb', line 107



def each(&block)
  @stack.each(&block)
end


  








  

    #new_constants  
  



  

    

Returns a list of new constants found since the last call to #watch_namespaces.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/dependencies.rb', line 117



def new_constants
  constants = []

  # Grab the list of namespaces that we're looking for new constants under
  @watching.last.each do |namespace|
    # Retrieve the constants that were present under the namespace when watch_namespaces
    # was originally called
    original_constants = @stack[namespace].last

    mod = Inflector.constantize(namespace) if Dependencies.qualified_const_defined?(namespace)
    next unless mod.is_a?(Module)

    # Get a list of the constants that were added
    new_constants = mod.constants(false) - original_constants

    # @stack[namespace] returns an Array of the constants that are being evaluated
    # for that namespace. For instance, if parent.rb requires child.rb, the first
    # element of @stack[Object] will be an Array of the constants that were present
    # before parent.rb was required. The second element will be an Array of the
    # constants that were present before child.rb was required.
    @stack[namespace].each do |namespace_constants|
      namespace_constants.concat(new_constants)
    end

    # Normalize the list of new constants, and add them to the list we will return
    new_constants.each do |suffix|
      constants << ([namespace, suffix] - ["Object"]).join("::".freeze)
    end
  end
  constants
ensure
  # A call to new_constants is always called after a call to watch_namespaces
  pop_modules(@watching.pop)
end


  








  

    #watch_namespaces(namespaces)  
  



  

    

Add a set of modules to the watch stack, remembering the initial constants.


  



  [ GitHub ]


  

  


# File 'activesupport/lib/active_support/dependencies.rb', line 154



def watch_namespaces(namespaces)
  @watching << namespaces.map do |namespace|
    module_name = Dependencies.to_constant_name(namespace)
    original_constants = Dependencies.qualified_const_defined?(module_name) ?
      Inflector.constantize(module_name).constants(false) : []

    @stack[module_name] << original_constants
    module_name
  end
end