Module: Changes::ClassMethods

Includes:
Gather::ClassMethods
Defined in:
lib/changes.rb

Instance Method Summary collapse

Methods included from Gather::ClassMethods

#own_properties, #properties

Instance Method Details

#blankslate! ⇒ Object

Remove all but the absolutely essential methods from this class. Useful if you want a dynamic property list, but can have some surprising side effects, obviously.



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# File 'lib/changes.rb', line 129

def blankslate!
  # remove unused methods that might clash with user accessors
  keep_methods = %w( __send__ __id__ self send class inspect instance_eval instance_variables )
  instance_methods.each do |method|
    undef_method( method ) unless keep_methods.include?( method )
  end
end

#dynamic! ⇒ Object 



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# File 'lib/changes.rb', line 268

def dynamic!; @dynamic = true; end

#dynamic? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/changes.rb', line 271

def dynamic?
  # don't optimise this to @dynamic ||= true, because it will reset
  # an @dynamic of false to true
  @dynamic = false if @dynamic.nil?
  @dynamic
end

#dynamic_properties(*syms) ⇒ Object

Allow accessors to be added dynamically, the default.



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# File 'lib/changes.rb', line 263

def dynamic_properties( *syms )
  @dynamic = true
  property( *syms )
end

#module_name(symbol) ⇒ Object 



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# File 'lib/changes.rb', line 137

def module_name( symbol )
  "#{symbol.to_s.capitalize}Property"
end

#operation(name, &body) ⇒ Object

define a method ‘name’ (which can be symbol or a string) which takes args and a block calls gather and then executes the block. Any changes made from args and block are rolled back name! will not roll back values



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# File 'lib/changes.rb', line 288

def operation( name, &body )
  # save the block to be executed later
  class_eval "@@#{name.to_s}_operation_block = body"
  
  # define the new method called name
  class_eval <<-EOF, __FILE__, __LINE__.to_i + 1
    def #{name.to_s}( args = {}, &block )
      preserve do
        gather( args, &block )
        instance_eval( &@@#{name.to_s}_operation_block )
      end
    end
  EOF
  
  # define new method called name!
  class_eval <<-EOF, __FILE__, __LINE__.to_i + 1
    def #{name.to_s}!( args = {}, &block )
      gather( args, &block )
      instance_eval( &@@#{name.to_s}_operation_block )
    end
  EOF
end

#property(*symbols) ⇒ Object

For each property in symbols, add methods:

instance.property as reader
instance.property( value ) as writer
instance.property = value as writer
instance.before_property {|old,new| ... }
instance.after_property {|old,new| ... }
instance.on_property {|old,new| ... }
instance.property_changed?
instance.undo_property!



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# File 'lib/changes.rb', line 150

def property( *symbols )
  @stripper ||= /^([^\= ]+)\s*\=?\s*$/
  symbols.each do |sym|
    property = @stripper.match( sym.to_s )[1]
    
    # TODO false here until I figure out how to remove properties
    unless false && const_defined?( module_name( property ).to_sym )
      own_properties << property.to_sym
      line, st = __LINE__, <<-EOF
        module #{module_name( property )}
        
        public
        def #{property}(*val)
          if val.empty?
            @#{property}
          else
            unwrapped_value = val.size == 1 ? val[0] : val
            self.#{property} = unwrapped_value
          end
        end
        
        def on_#{property}( &block )
          @on_#{property}_block = block
        end
        
        def after_#{property}( &block )
          @after_#{property}_block = block
        end
        
        def before_#{property}( &block )
          @before_#{property}_block = block
        end
        
        def #{property}=(*new_value)              
          unwrapped_value = new_value.size == 1 ? new_value[0] : new_value
          return if unwrapped_value == @#{property}
          
          @before_#{property}_block.call_if( @#{property}, unwrapped_value )
          
          changes[:#{property}] ||= Change.new
          changes[:#{property}].old << @#{property}
          changes[:#{property}].new = unwrapped_value
          
          @#{property} = unwrapped_value
          
          @after_#{property}_block.call_if( changes[:#{property}].old, unwrapped_value )
          @on_#{property}_block.call_if( changes[:#{property}].old, unwrapped_value )
          on_change( :#{property}, changes[:#{property}].old, unwrapped_value )
        end
        
        def #{property}_changed?
          changes.has_key?(:#{property}) && !changes[:#{property}].old.empty?
        end
        
        # Undo the last change and return the undone value.
        # return nil if there were no changes to undo
        def undo_#{property}!
          undo( :#{property} )
        end
        
        def reset_#{property}!
          changes[x] = Change.new
        end
        
        private
        def direct_#{property}=( value )
          @#{property} = value
        end
        
        end # module
      EOF
      class_eval st, __FILE__, line + 1
    end
    
    # always include the module, for re-definitions
    class_eval "include #{property.capitalize}Property"
  end
end

#static! ⇒ Object 



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# File 'lib/changes.rb', line 269

def static!; @dynamic = false; end

#static_properties(*syms) ⇒ Object

Do not allow accessors to be added dynamically. In other words, a subclass like this

class IndexCollector
  static_properties :row, :column
end

will fail if used like this

collector = IndexCollector.new( :row => 4, :column => 6 ) do
  other 'oops'
end

because :other isn’t added by static_properties.



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# File 'lib/changes.rb', line 257

def static_properties( *syms )
  @dynamic = false
  property( *syms )
end