Design Patterns - Revision history

Joachim: /* State Pattern */

2024-07-08T14:07:02Z

State Pattern

← Older revision		Revision as of 14:07, 8 July 2024
Line 23:		Line 23:
	It is in the category of behavioral patterns.		It is in the category of behavioral patterns.

	The base class state interface has one or more operation methods.		The base class state interface has one or more operation methods and a context saving the current state and providing a setState() method.
	Different derived states can implement operations differently.		Different derived states can implement operations differently.
	The context object saves a base class reference to its current state and provides a method to change the current state		The context object saves a base class reference to its current state and provides the method to change the current state.
			Operations are always called with the context objects current state reference.
			The operations can change the current state of the context object as required

Joachim: /* State Pattern */

2024-07-08T14:01:22Z

State Pattern

← Older revision		Revision as of 14:01, 8 July 2024
Line 18:		Line 18:
	== State Pattern ==		== State Pattern ==

	Use it for objects that change behaviour depending on internal state.		Use it for context dependent objects that change behaviour depending on internal state.
	E.g. a switch that acts differently on toggle() if the light is on or off.		E.g. a switch that acts differently on toggle() if the light is on or off.
	It makes sure that new states don't affect the objects behaviour of existing states.		The pattern makes sure that new states don't affect the objects behaviour of existing states.
			It is in the category of behavioral patterns.

	The base class state interface has ~~some~~ operation~~() method~~.		The base class state interface has one or more operation methods.
	Different derived states can implement ~~operation()~~ differently.		Different derived states can implement operations differently.
			The context object saves a base class reference to its current state and provides a method to change the current state
	The ~~state~~ context ~~always calls the~~ base state ~~operation()~~ and ~~remembers~~ the ~~currently active derived~~ state

Joachim: /* State Pattern */

2024-07-08T13:43:47Z

State Pattern

← Older revision		Revision as of 13:43, 8 July 2024
Line 17:		Line 17:

	== State Pattern ==		== State Pattern ==

			Use it for objects that change behaviour depending on internal state.
			E.g. a switch that acts differently on toggle() if the light is on or off.
			It makes sure that new states don't affect the objects behaviour of existing states.

			The base class state interface has some operation() method.
			Different derived states can implement operation() differently.

			The state context always calls the base state operation() and remembers the currently active derived state

Joachim: Created page with "= Design Patterns = == Dispatcher Pattern == * Use a dispatcher if you want to run code in another thread * A dispatcher has two interfaces: one to add code to execute to a list and one to process the list * The dispatcher client interface is an invoke() method to schedule code execution in another thread. It just adds the code to a list. * In the other thread there is a method like invokePending() going through the list and execute the code * The dispatcher implementa..."

2024-07-08T13:11:44Z

Created page with "= Design Patterns = == Dispatcher Pattern == * Use a dispatcher if you want to run code in another thread * A dispatcher has two interfaces: one to add code to execute to a list and one to process the list * The dispatcher client interface is an invoke() method to schedule code execution in another thread. It just adds the code to a list. * In the other thread there is a method like invokePending() going through the list and execute the code * The dispatcher implementa..."

New page

= Design Patterns =

== Dispatcher Pattern ==

* Use a dispatcher if you want to run code in another thread
* A dispatcher has two interfaces: one to add code to execute to a list and one to process the list
* The dispatcher client interface is an invoke() method to schedule code execution in another thread. It just adds the code to a list.
* In the other thread there is a method like invokePending() going through the list and execute the code
* The dispatcher implementation can be a singleton to ensure invoke() and invokePending work with the same list

== Singleton ==

Use if there should be just one object of a class
* create a class with only private constructor(s)
* users of the object can get it with a static get() interface method from the class
* the get method first checks if the object already exists. If not, it creates it with a private constructor and saves it e.g. as a private pointer. Finally it returns the saved object

== State Pattern ==