Class: Hashery::PropertyHash

Inherits:
Hash show all
Defined in:
lib/hashery/property_hash.rb

Overview

A PropertyHash is the same as a regular Hash except it strictly limits the allowed keys.

There are two ways to use it.

1) As an object in itself.

h = PropertyHash.new(:a=>1, :b=>2)
h[:a]        #=> 1
h[:a] = 3
h[:a]        #=> 3

But if we try to set key that was not fixed, then we will get an error.

h[:x] = 5    #=> ArgumentError

2) As a superclass.

class MyPropertyHash < PropertyHash
  property :a, :default => 1
  property :b, :default => 2
end

h = MyPropertyHash.new
h[:a]        #=> 1
h[:a] = 3
h[:a]        #=> 3

Again, if we try to set key that was not fixed, then we will get an error.

h[:x] = 5    #=> ArgumentError

Class Method Summary (collapse)

Instance Method Summary (collapse)

Methods inherited from Hash

#to_keyhash, #to_stash

Methods included from CoreExt

#rekey, #rekey!, #to_h, #to_hash

Constructor Details

- (PropertyHash) initialize(properties = {})

A new instance of PropertyHash



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# File 'lib/hashery/property_hash.rb', line 55

def initialize(properties={})
  super()
  fixed = self.class.properties.merge(properties)
  replace(fixed)
end

Class Method Details

+ (Object) properties 



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# File 'lib/hashery/property_hash.rb', line 38

def self.properties
  @properties ||= (
    parent = ancestors[1]
    if parent.respond_to?(:properties)
      parent.properties
    else
      {}
    end
  )
end

+ (Object) property(key, opts = {}) 



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# File 'lib/hashery/property_hash.rb', line 50

def self.property(key, opts={})
  properties[key] = opts[:default]
end

Instance Method Details

- (Object) <<(a) 



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# File 'lib/hashery/property_hash.rb', line 80

def <<(a)
  k,v = *a
  self[k] = v
end

- (Object) []=(k, v) 



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# File 'lib/hashery/property_hash.rb', line 62

def []=(k,v)
  assert_key!(k)
  super(k,v)
end

- (Object) accept_key!(k, v = nil)

Add a new acceptable key. TODO: Should this be supported?



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# File 'lib/hashery/property_hash.rb', line 87

def accept_key!(k,v=nil)
  self[k] = v
end

- (Object) merge!(h) 



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# File 'lib/hashery/property_hash.rb', line 74

def merge!(h)
  h.keys.each{ |k| assert_key!(k) }
  super(h)
end

- (Object) update(h) 



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# File 'lib/hashery/property_hash.rb', line 68

def update(h)
  h.keys.each{ |k| assert_key!(k) }
  super(h)
end