Quote:
Originally Posted by Ether
The way you worded that doesn't clearly answer my question.
Let me try re-wording it:
You can create something called a CommandGroup which contains a sequence of commands, intended to be executed one after another. The scheduler will queue the first of those commands, then queue the next command when the previous one has completed, and so on until all the commands in the group have been so queued (and therefore run in sequence). The Command Based API has a WaitCommand. The WaitCommand is not queued. Rather, when the scheduler encounters a WaitCommand in a CommandGroup, the scheduler does not queue the command following the WaitCommand until the specified time has expired.
I have no idea if the above description is an accurate account of what the Command Based implementation actually does, but is that what you meant?
That's a sort of state machine, with time being the state variable.
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I'm sorry, I'll try to be more descriptive since I don't think I provided enough information. Btw, I hope the presentation I sent you earlier in the build season was helpful.
The scheduler keeps a list of currently running commands on the system. The execution happens as follows:
1. Gets next command in the list
2. If this is the first time this command is going to run, execute the commands initialize().
3. Execute the command's execute().
4. Execute the command's isFinished(), if the method returns true execute the commands end(), otherwise add the command back onto the list at the end.
5. Repeat steps 1-4.
For the system to work the commands methods need to execute quickly. This means not putting in any waits in the code or the scheduler will not not move onto the next command.
Now, onto the WaitCommand I was talking about before. The CommandGroup allows you to add commands to run in sequence, below is an example that will deploy and arm, wait 5 seconds, then retract the arm.
Code:
addSequential(new DeployArmCommand());
addSequential(new WaitCommand(5));
addSequential(new RetractArmCommand());
How does this work? Good question. The first command DeployArmCommand is added to the scheduler's list for execution. Since the Scheduler is constantly running this will cause the command to start executing in the normal sequence along with any other commands currently running. Once the DeployArmCommand returns a true value from its isFinished() the next command, which is the WaitCommand, will be added to the Scheduler's list. I'm assuming the wait command is set up as a sort of state machine as discussed earlier which will return a true value from its isFinished() once the specified time in seconds has elapsed.
I hope this makes it clearer than I described earlier. If you need any more clarification on anything let me know.