Participants 1 Model The part that does the actual computation, - - PowerPoint PPT Presentation

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Participants 1 Model The part that does the actual computation, - - PowerPoint PPT Presentation

Oct 16, 2022 46 likes •197 views

Model View Controller Pattern Behavioural Intent Partition user-interactive applications into three parts > Model > View > Controller Motivation Use divide and conquer to simplify

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SLIDE 1

MVC-1

Model View Controller Pattern – Behavioural

  • Intent

» Partition user-interactive applications into three

parts

> Model > View > Controller


  • Motivation

» Use divide and conquer to simplify interactions

among the parts of a program

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SLIDE 2

MVC-2

Participants – 1

  • Model

» The part that does the actual computation, data

manipulation and processing

  • View

» The purely graphical part of the application, taking

care of presenting information visually and interacting with users. Notions such as buttons,

  • ther controls and events belong here
  • Controller

» Connects the model with the view by specifying

what operations from the model must be executed in response to what user events occur

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SLIDE 3

MVC-3

Participants – 2

  • Controller

Model View

Diagrams based on Stanford CS193p Fall 2011 slides

What your application is Mediates between the model and the view How a user sees and accesses the model

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SLIDE 4

MVC-4

Communications

  • It’s all about managing the communications

Controller View Model

Model and view never talk directly to each other Controller can always talk to the model and view

  • utlet
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SLIDE 5

MVC-5

Communications – Model

  • Controller

View Model

Model has a radio station to broadcast
 change notifications

  • Models can only communicate directly with other models

Controllers (and other models) tune into stations in which they are interested

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SLIDE 6

MVC-6

Communications – View – 1 of 3

  • Target method

Action – button, gesture

Controller View Model

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SLIDE 7

MVC-7

Communications – View – 2 of 3

  • Controller sets itself as view’s delegate

View asks controller to do work, indirectly as its delegate,
 and notifies the controller when
 the view changes

Controller View Model

should, will, did

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SLIDE 8

MVC-8

Communications – View – 3 of 3

  • Controller sets itself as view’s data source

View asks controller for the data it needs

Controller View Model

data, at, count

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SLIDE 9

MVC-9

Multiple MVC patterns

  • Controller

Controller Model Controller View Model Controller View Controller View Model Controller View Model

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SLIDE 10

MVC-10

Hello World Example

  • Spaceling

No model

sayHelloButton

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SLIDE 11

MVC-11

Calculator Example

  • delegate for “back” button

data source

If the calculator has the data source protocol expected by the graphing function, then it could be the data source

Calculator_view_controller Function_graph_vc Calculator

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SLIDE 12

MVC-12

Participants

  • Model

Has all the data and methods for maintaining the data

  • View

Displays relevant data, accepts user actions and notifies controller

  • Controller

» Reacts to changes in the model to instruct how the

view is to change

» Reacts to view “actions” to instruct the view how

to change and to instruct how the model is to change

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SLIDE 13

MVC-13

Applicability

  • Use MVC in all interactive applications
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SLIDE 14

MVC-14

Consequences

  • The accepted way to deal with interactive

applications

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SLIDE 15

MVC-15

Related Patterns

  • MVC is a special case of the Mediator pattern

» The controller is the mediator between the model

and the view

  • MVC has similarities to the Observer pattern.