Home

Command

Problem

A functionality must be exposed in to the UI to be perceived by the user as available. The command encapsulates this functionality wrapping.

Principle

Functionality exposure.

Forces

Solution

The command will encapsulate the access to the functionality. A command should be unequivocally recognizable: it can be accessed using different styles of interaction & context, however a command should be exposed consistently to allow the user to recognize the different short-cuts to the same functionality.

A command can be seen also in an application, as the minimal unit of change that can be produced in a system. When available, undo functionality can be used to come back to a previous state in case of errors.

Rationale

The command groups functionality in packets and provides a unique name. The user recognize the name, it symbol (e.g. icon or sound) and remembers the functionality associated to.

Command Sample 1
Figure 1. Microsoft Word™ Bold command
representation in the toolbar.

Examples

Menu items in a menu, items in a palette toolbox or links in a web menu can be examples of commands. A common example can be seen in Office applications like Microsoft Word™. It offer its commands in different alternative ways at the same time. For example, the command for Bold is offered in three ways:

  1. In the main menu: Format → Font → Font → Bold
  2. In the toolbar: Format → Bold (Figure 1)
  3. As an accelerator Key: Ctlr-B (in the English localized version)

Specification

A unique name and optionally: symbols (e.g. icons, sounds, glyphs) will represent the command in the User Interface.






Root CUIP Metalevel

Valid XHTML 1.0 Strict Valid CSS