# validated: 2018-01-06 TW 8346caed9cbf edu/wpi/first/wpilibj/command/Subsystem.java
#----------------------------------------------------------------------------
# Copyright (c) FIRST 2008-2012. All Rights Reserved.
# Open Source Software - may be modified and shared by FRC teams. The code
# must be accompanied by the FIRST BSD license file in the root directory of
# the project.
#----------------------------------------------------------------------------
import logging
from .scheduler import Scheduler
from ..livewindow import LiveWindow
from ..sendablebase import SendableBase
__all__ = ["Subsystem"]
[docs]class Subsystem(SendableBase):
"""This class defines a major component of the robot.
A good example of a subsystem is the driveline, or a claw if the robot has
one.
All motors should be a part of a subsystem. For instance, all the wheel
motors should be a part of some kind of "Driveline" subsystem.
Subsystems are used within the command system as requirements for Command.
Only one command which requires a subsystem can run at a time. Also,
subsystems can have default commands which are started if there is no
command running which requires this subsystem.
.. seealso:: :class:`.Command`
"""
def __init__(self, name=None):
"""Creates a subsystem.
:param name: the name of the subsystem; if None, it will be set to the
name to the name of the class.
"""
super().__init__()
# The name
if name is None:
name = self.__class__.__name__
self.setName(name)
Scheduler.getInstance().registerSubsystem(self)
self.logger = logging.getLogger(__name__)
# Whether or not getDefaultCommand() was called
self.initializedDefaultCommand = False
# The current command
self.currentCommand = None
self.currentCommandChanged = True
# The default command
self.defaultCommand = None
[docs] def initDefaultCommand(self):
"""Initialize the default command for a subsystem
By default subsystems have no default command, but if they do, the
default command is set with this method. It is called on all
Subsystems by CommandBase in the users program after all the
Subsystems are created.
"""
pass
[docs] def periodic(self):
"""When the run method of the scheduler is called this method will be called.
"""
func = self.periodic.__func__
if not hasattr(func, "firstRun"):
self.logger.info("Default Subsystem.periodic() method... Overload me!")
func.firstRun = False
[docs] def setDefaultCommand(self, command):
"""Sets the default command. If this is not called or is called with
None, then there will be no default command for the subsystem.
:param command: the default command (or None if there should be none)
.. warning:: This should NOT be called in a constructor if the subsystem
is a singleton.
"""
if command is None:
self.defaultCommand = None
else:
if self not in command.getRequirements():
raise ValueError("A default command must require the subsystem")
self.defaultCommand = command
[docs] def getDefaultCommand(self):
"""Returns the default command (or None if there is none).
:returns: the default command
"""
if not self.initializedDefaultCommand:
self.initializedDefaultCommand = True
self.initDefaultCommand()
return self.defaultCommand
[docs] def getDefaultCommandName(self):
"""
Returns the default command name, or empty string is there is none.
:returns: the default command name
"""
defaultCommand = self.getDefaultCommand()
if defaultCommand is not None:
return defaultCommand.getName()
return ""
[docs] def setCurrentCommand(self, command):
"""Sets the current command
:param command: the new current command
"""
self.currentCommand = command
self.currentCommandChanged = True
[docs] def confirmCommand(self):
"""Call this to alert Subsystem that the current command is actually
the command. Sometimes, the Subsystem is told that it has no command
while the Scheduler is going through the loop, only to be soon after
given a new one. This will avoid that situation.
"""
if self.currentCommandChanged:
self.currentCommandChanged = False
[docs] def getCurrentCommand(self):
"""Returns the command which currently claims this subsystem.
:returns: the command which currently claims this subsystem
"""
return self.currentCommand
[docs] def getCurrentCommandName(self):
"""
Returns the current command name, or empty string if no current command.
:returns: the current command name
"""
currentCommand = self.getCurrentCommand()
if currentCommand is not None:
return currentCommand.getName()
return ""
[docs] def addChild(self, child, name=None):
"""
Associate a :class:`.Sendable` with this Subsystem.
Update the child's name if provided
:param child: sendable
:param name: name to give child
"""
if name is not None:
child.setName(self.getSubsystem(), name)
else:
child.setSubsystem(self.getSubsystem())
LiveWindow.add(child)
def __str__(self):
return self.getSubsystem()
[docs] def initSendable(self, builder):
builder.setSmartDashboardType("Subsystem")
builder.addBooleanProperty(".hasDefault", lambda: self.defaultCommand is not None, None)
builder.addStringProperty(".default", self.getDefaultCommandName, None)
builder.addBooleanProperty(".hasCommand", lambda: self.defaultCommand is not None, None)
builder.addStringProperty(".command", self.getCurrentCommandName, None)