ParentChild Lingo

1
Parent-Child Lingo

• An Intro to Object-oriented Programming

2
Basic OOP Concept

• Encapsulation of features (properties) and
  actions (handlers)

Object 1 Data Methods
Object 2 Data Methods
3
Parent/Child Lingo

• Parent
• Represents prototype (class)doesnt actually
  exist
• Defines properties of that object type
  (equivalent to local variables)
• Defines custom handlers/functions for that object
  type
• Definitions placed in a parent script

4
Parent/Child Lingo

• Child
• An instance of an object
• Contains a unique copy of the properties,
  handlers
• Created using new function
• myObject new(parentScript)
• Exist in RAM, not in Score or Cast, though
  objects can be assigned to sprites

5
Example Note

• Properties
• pitch
• duration
• note head
• stem direction
• location
• attached elements
• accidentals
• articulations
• dots

• Handlers
• Change location
• Change stem direction
• Change pitch
• Change duration

6
Why OOP?

• Helps manage complexity
• keeps related Lingo code together
• Note parent needs to know only about notes,
  and knows everything about notes
• Provides for reusable components
• a score includes multiple notes
• can change internal implementation without
  affecting external access

7
Example Math drill
8
Writing a Parent Script

• Create a new script
• Set its type to Parent
• Declare properties first
• Include an on new handler that is called when a
  new object is created
• may include initialization parameters
• Provide handlers to set/retrieve property values

9
Creating a Child Object

• use the New function
• keyword script and name of the parent script is
  first parameter
• initialization variables for the on new handler
  follow
• assign result of function to a variable or add it
  to a list
• myObject new(script parentScriptName, param)