Module: Changes

Includes:
Gather
Defined in:
lib/changes.rb

Overview

Same as Gather, except that history is kept for changes, and on_change is called each time a property value changes.

Defined Under Namespace

Modules: ClassMethods Classes: Change

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Gather

#[], #[]=, #each, #gather, #merge, #merge!, #to_hash

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(sym, *args) ⇒ Object

Add the property methods if they don’t already exist, and if dynamic is in effect, which is the default. If static is in effect, the normal method_missing behaviour will be invoked.



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# File 'lib/changes.rb', line 110

def method_missing(sym, *args)
  if self.class.dynamic?
    self.class.property sym
    send( sym, *args )
  else
    super
  end
end

Instance Attribute Details

#change_history ⇒ Object 



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# File 'lib/changes.rb', line 57

def change_history
  @change_history ||= []
end

Class Method Details

.included(base) ⇒ Object 



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# File 'lib/changes.rb', line 311

def self.included( base )
  base.extend( ClassMethods )
end

Instance Method Details

#changed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/changes.rb', line 39

def changed?
  changes.empty?
end

#changes(*symbols) ⇒ Object 



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# File 'lib/changes.rb', line 43

def changes( *symbols )
  if symbols.empty?
    @changes ||= {}
  else
    symbols.map{|x| changes[x] }
  end
end

#init_properties(hash, &block) ⇒ Object

should probably use an object creation hook to do this



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# File 'lib/changes.rb', line 34

def init_properties( hash, &block )
  @changes = {}
  gather( hash, &block )
end

#initialize(hash = {}, &block) ⇒ Object 



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# File 'lib/changes.rb', line 28

def initialize( hash = {}, &block )
  init_properties( hash, &block )
end

#mark ⇒ Object

make a mark in the change history



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# File 'lib/changes.rb', line 62

def mark
  new_changes = @changes.clone
  new_changes.each{|k,v| new_changes[k] = v.clone}
  change_history << new_changes
end

#on_change(property, old, new) ⇒ Object

called after the property has changed including classes should define this



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# File 'lib/changes.rb', line 53

def on_change( property, old, new )
end

#preserve(*symbols) ⇒ Object

execute the block, undo the given symbols, and return the result of the executed block. If no symbols are given, just use mark and restore



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# File 'lib/changes.rb', line 85

def preserve( *symbols )
  mark if symbols.empty?
  retval = yield
  if symbols.empty?
    restore
  else
    symbols.each {|symbol| undo( symbol ) }
  end
  retval
end

#property_names ⇒ Object

Return a collection of property symbols



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# File 'lib/changes.rb', line 120

def property_names
  self.class.properties.to_a
end

#reset!(*properties) ⇒ Object

reset the passed properties, or all if none are specified



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# File 'lib/changes.rb', line 74

def reset!( *properties )
  if properties.empty?
    @changes = {}
  else
    properties.each {|x| changes[x] = Change.new}
  end
end

#restore ⇒ Object

restore the last mark. Do not emit any changes.



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# File 'lib/changes.rb', line 69

def restore
  @changes = change_history.pop unless change_history.empty?
end

#undo(symbol) ⇒ Object 



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# File 'lib/changes.rb', line 96

def undo( symbol )
  unless changes[symbol].old.empty?
    current = send( symbol )
    if changes[symbol] && changes[symbol].old
      eval "@#{symbol.to_s} = changes[:#{symbol.to_s}].old.pop"
    end
    current
  end
end