Class: Constants::ConstantLibrary::Collection

Inherits:
Array
  • Object
show all
Includes:
Stash
Defined in:
lib/constants/constant_library.rb

Overview

An array-based Stash for collections of library objects.

– Note: comparison of Index and Collection indicates that these are highly related classes. Why no exclusion value and why no modifiable nil_value for Collection? Simply because an array ALWAYS returns nil for uninitialized locations (esp out-of-bounds locations). This means that Stash, which uses the value at self[] to determine when to stash and when not to stash, must have nil as it’s nil_value to behave correctly. Effectively treating nil as an exclusion value for collection works well in this case since nils cannot be stashed.

Hashes (ie Index) do not share this behavior. Since you can define a default value for missing keys, self[] can return something other than nil… hence there is an opportunity to use non-nil nil_values and non-nil exclusion values.

Instance Attribute Summary collapse

Attributes included from Stash

#nil_value

Instance Method Summary collapse

Constructor Details

#initialize(&block) ⇒ Collection

Initializes a new Collection (a type of Array). The block is used by stash to calculate the values in a collection.



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# File 'lib/constants/constant_library.rb', line 88

def initialize(&block)
  super(&nil)
  @nil_value = nil
  @block = block
end

Instance Attribute Details

#block ⇒ Object (readonly)

The block used to calculate keys during stash



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# File 'lib/constants/constant_library.rb', line 84

def block
  @block
end

Instance Method Details

#stash(values) ⇒ Object

Stashes the specified values in self using values calculated by the block. Values are skipped if the block returns nil.

See Constants::ConstantLibrary#collect for more details.



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# File 'lib/constants/constant_library.rb', line 98

def stash(values)
  values.each do |value| 
    value, index = block.call(value)
    next if value == nil
  
    super(index == nil ? self.length : index, value)
  end
  
  self
end