Creating selections and commands

Selections and commands work in combination to modify a data model--the selection specifies some portion of data within the model, and the command operates on the model through the selection. The CommonPoint programming model advocates using this technique instead of directly updating the data model, because it makes possible features such as:

Multiple levels of undo and redo
Saveless model
Document recovery after crashes
Scripting
Collaboration

This step demonstrates how to add support for selecting tiles within a TTilesModel and issuing a command to change the color of a selected tile. You'll learn how to:

Design and implement a selection
Design and implement an undoable command
Issue a command

Selecting a tile and issuing a command
Creating the selection class
Creating the command class
Code walkthrough

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