- Parameters to initialize:
- good if there are only a few common parameters that are used almost everytime
file = File.new( "foo.txt", "r" )
- Hash parameter to initialize:
- nice if there are only a few parameters and most parameters have defaults
- nice because it names the parameters (more verbose)
- order of parameters doesn't matter
db = Ramen.new ( :connection => my_connection, :engine => Sql2005 )
- Context block
- useful when there are many configuration options needed
- can operate like a DSL by providing methods on the block parameter (conf in the example below)
- can easily configure multiple closures
- provides a lexical scope where the configuration object is valid, but the obj being created is not ready for use.
obj = SomeObject.new do | conf |
conf.option1 = 'foo'
conf.option2 = bar
conf.select :everything
conf.blockOne { |a| puts a }
conf.blockTwo { |a| pp a }
end
- Properties
- poor style
- not clear when the obj is ready for use.
- configuration could get changed later by accidentally setting config properties at the wrong time.
obj = SomeObject.new
obj.option1 = 'foo'
obj.option2 = bar
obj.select :everything
- Prototype
- not commonly used
- useful when creating lots of similar objects
- automatically calls initialize_copy method on the new object
obj = another_object.clone # copies everything: state, singleton methods, etc
obj = another_object.dup # copies state and tainted?
o = Object::const_get( class_name ).allocate
class_props.each_pair { |k,v| o.instance_eval "@#{k} = v" }
