Programmation orientée commande

Ces articles servent d’introduction et de référence pour le cadre d’application orienté commande de WPILib.

Pour un ensemble d’exemples de projets qui utilisent le cadre d’application orienté commande, consultez Exemples de programmes basés sur l’architecture orientée Commande.

• Qu’est-ce que la programmation « orientée commande » ?
• Commandes
• Command Compositions
• Les sous-systèmes
• Liaison de commandes à des déclencheurs
• Structurer un projet de robot orienté commande
• Organizing Command-Based Robot Projects
• Le planificateur de commandes
• Une discussion technique sur les commandes C++
• Contrôle PID via PIDSubsystems et PIDCommands
• Profilage de mouvement via TrapezoidProfileSubsystems et TrapezoidProfileCommands
• Combinaison du profilage de mouvement et du PID dans les commandes

Passing Functions As Parameters

In order to provide a concise inline syntax, the command-based library often accepts functions as parameters of constructors, factories, and decorators. Fortunately, both Java and C++ offer users the ability to pass functions as objects:

Method References (Java)

In Java, a reference to a function that can be passed as a parameter is called a method reference. The general syntax for a method reference is object::method. Note that no method parameters are included, since the method itself is passed. The method is not being called - it is being passed to another piece of code (in this case, a command) so that that code can call it when needed. For further information on method references, see Références de méthodes.

Lambda Expressions (Java)

While method references work well for passing a function that has already been written, often it is inconvenient/wasteful to write a function solely for the purpose of sending as a method reference, if that function will never be used elsewhere. To avoid this, Java also supports a feature called « lambda expressions. » A lambda expression is an inline method definition - it allows a function to be defined inside of a parameter list. For specifics on how to write Java lambda expressions, see Expressions Lambda en Java.

Lambda Expressions (C++)

Avertissement

Due to complications in C++ semantics, capturing this in a C++ lambda can cause a null pointer exception if done from a component command of a command composition. Whenever possible, C++ users should capture relevant command members explicitly and by value. For more details, see here.

C++ lacks a close equivalent to Java method references - pointers to member functions are generally not directly usable as parameters due to the presence of the implicit this parameter. However, C++ does offer lambda expressions - in addition, the lambda expressions offered by C++ are in many ways more powerful than those in Java. For specifics on how to write C++ lambda expressions, see Expressions lambda en C++.