README.md

Programs: ./build/bin/ap (everything in one class), ./build/bin/mvc_ap, ./build/bin/mvvm_ap. They are built only when gtkmm-4.0 is installed (CPPLAB_BUILD_GUI).

Architecture Patterns

1. MVVM

• MVVM (Model - View - ViewModel) is an architecture pattern that separates the user interface (View) from the business logic and data (Model) through an intermediary component called the ViewModel

• Components:

  • Model: responsible for managing and abstracting data sources (databases, APIs, ..). Model and ViewModel work together to get and save the data.
  • View: displays data provided by the ViewModel and informs the ViewModel about user actions. This layer observes the ViewModel and does not contain application logic.
  • ViewModel: exposes data and state that are relevant to the View, and transforms data from Model into a suitable format. Moreover, it serves as a link between the Model and the View.
  • Binder (Data Binding): connects the View and the ViewModel, automatically synchronizing data between them. This mechanism allows the View to update when the ViewModel changes, and vice versa.

• Workflow:

  1. User interacts with the View (e.g., clicks a button).
  2. The View notifies the ViewModel.
  3. The ViewModel processes the input, applies logic, and may request data from the Model.
  4. The Model fetches or updates the data (e.g., from an API or database).
  5. The Model sends data back to the ViewModel.
  6. The ViewModel updates the observable data, which automatically updates the View through data binding or observers.

User
 |
 v
View <-> ViewModel <-> Model    # view automatically update
       (data binding)

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2. MVC

• MVC (Model - View - Controller) is an architectural pattern that separates the user interface (View) from the application logic and data (Model) using an intermediary component called the Controller.

• Components:

  • Model: is responsible for managing and abstracting data sources (databases, APIs, etc.). The Model handles data retrieval, storage, and business logic.
  • View: displays the data provided by the Model and represents the user interface. The View is responsible only for presentation and does not contain business logic.
  • Controller: acts as an intermediary between the View and the Model. It receives user input from the View, processes it, and interacts with the Model to update or retrieve data. The Controller then determines which View should display the result.

• Workflow:

  1. User interacts with the View (e.g., clicks a button).
  2. The View sends the user input to the Controller.
  3. The Controller processes the input, performs business logic, and may update the Model.
  4. The Model updates its data (e.g., saves to a database or gets data from an API).
  5. The Controller then updates the View based on the new Model data.

User
 |
 v
View -> Controller -> Model
            |
            v
           View # view update manually

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3. GTK4

• Refer

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4. Trade-offs: MVC vs MVVM

Aspect	MVC	MVVM
Complexity	Lower — Controller is a thin pass-through	Slightly higher — ViewModel adds an extra layer
Coupling	Views know both Controller and Model (e.g., for initial data)	Views know only the ViewModel
Testability	Controller is testable, but Views are still tied to Model for reads	ViewModel is fully testable without GTK; Views are pure UI
Scalability	Adding fields requires updating Model, Controller, and all Views	Adding fields requires updating Model and ViewModel; Views update bindings only
Observer wiring	Manual — Container wires each View to the Model	Self-contained — Views register via ViewModel; container stays clean
UI logic leakage	Risk - Views may call model_->getData() directly	Eliminated - Views use viewModel_->getCurrentText() only