[commands] Refactor ProxyScheduleCommand, SelectCommand into ProxyCommand (#4534)

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/Command.java

@@ -286,14 +286,14 @@ public interface Command {
   }
 
   /**
-   * Decorates this command to run "by proxy" by wrapping it in a {@link ProxyScheduleCommand}. This
-   * is useful for "forking off" from command groups when the user does not wish to extend the
+   * Decorates this command to run "by proxy" by wrapping it in a {@link ProxyCommand}. This is
+   * useful for "forking off" from command groups when the user does not wish to extend the
    * command's requirements to the entire command group.
    *
    * @return the decorated command
    */
-  default ProxyScheduleCommand asProxy() {
-    return new ProxyScheduleCommand(this);
+  default ProxyCommand asProxy() {
+    return new ProxyCommand(this);
   }
 
   /**

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/ProxyCommand.java

@@ -0,0 +1,76 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.wpilibj2.command;
+
+import static edu.wpi.first.wpilibj.util.ErrorMessages.requireNonNullParam;
+
+import java.util.function.Supplier;
+
+/**
+ * Schedules the given command when this command is initialized, and ends when it ends. Useful for
+ * forking off from CommandGroups. If this command is interrupted, it will cancel the command.
+ *
+ * <p>This class is provided by the NewCommands VendorDep
+ */
+public class ProxyCommand extends CommandBase {
+  private final Supplier<Command> m_supplier;
+  private Command m_command;
+
+  /**
+   * Creates a new ProxyCommand that schedules the supplied command when initialized, and ends when
+   * it is no longer scheduled. Useful for lazily creating commands at runtime.
+   *
+   * @param supplier the command supplier
+   */
+  public ProxyCommand(Supplier<Command> supplier) {
+    m_supplier = requireNonNullParam(supplier, "supplier", "ProxyCommand");
+  }
+
+  /**
+   * Creates a new ProxyCommand that schedules the given command when initialized, and ends when it
+   * is no longer scheduled.
+   *
+   * @param command the command to run by proxy
+   */
+  public ProxyCommand(Command command) {
+    this(() -> command);
+  }
+
+  @Override
+  public void initialize() {
+    m_command = m_supplier.get();
+    m_command.schedule();
+  }
+
+  @Override
+  public void end(boolean interrupted) {
+    if (interrupted) {
+      m_command.cancel();
+    }
+    m_command = null;
+  }
+
+  @Override
+  public void execute() {}
+
+  @Override
+  public boolean isFinished() {
+    // because we're between `initialize` and `end`, `m_command` is necessarily not null
+    // but if called otherwise and m_command is null,
+    // it's UB, so we can do whatever we want -- like return true.
+    return m_command == null || !m_command.isScheduled();
+  }
+
+  /**
+   * Whether the given command should run when the robot is disabled. Override to return true if the
+   * command should run when disabled.
+   *
+   * @return true. Otherwise, this proxy would cancel commands that do run when disabled.
+   */
+  @Override
+  public boolean runsWhenDisabled() {
+    return true;
+  }
+}

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/ProxyScheduleCommand.java

@@ -22,7 +22,10 @@ public class ProxyScheduleCommand extends CommandBase {
    * when they are all no longer scheduled.
    *
    * @param toSchedule the commands to schedule
+   * @deprecated Replace with {@link ProxyCommand}, composing multiple of them in a {@link
+   *     ParallelRaceGroup} if needed.
    */
+  @Deprecated
   public ProxyScheduleCommand(Command... toSchedule) {
     m_toSchedule = Set.of(toSchedule);
   }

wpilibNewCommands/src/main/java/edu/wpi/first/wpilibj2/command/SelectCommand.java

@@ -63,7 +63,9 @@ public class SelectCommand extends CommandBase {
    * Creates a new selectcommand.
    *
    * @param toRun a supplier providing the command to run
+   * @deprecated Replace with {@link ProxyCommand}
    */
+  @Deprecated
   public SelectCommand(Supplier<Command> toRun) {
     m_commands = null;
     m_selector = null;