18-642 Project 3

Updated 8/15/2022. Changelog

Learning objective: experience cleaning up code to conform to an externally imposed prescriptive coding style (a common industry objective).

This project takes your code from Project 2 and asks you to take concrete steps to clean it up. We ask you to follow a checklist, and to compare the changes you make in project 3 to the ones you made in project 2.

• If you are not proficient at using command line tools and scripting or other software development processes, we suggest you watch lectures 1-8 of the MIT "Missing Semester" class:
  https://www.youtube.com/watch?v=Z56Jmr9Z34Qlist=PLyzOVJj3bHQuloKGG59rS43e29ro7I57Jindex=2t=0s

Lab Files:

• Virtualbox image (changelog/hints). Be sure to check Canvas announcements and use the latest image in case changes have been made.
• Code style checklist

Hints/Helpful Links:

• See the Recitation video and slides on Canvas
• Please follow the handin naming convention: every filename (before the file extension) must end in [FAMILYNAME]_[GivenName]_[AndrewID].
• Don't forget to look at recitation slides!
• The turtle simulation is meant to represent a simplified PHYSICAL system. That means spinning or moving takes time and space. Just because a simulator lets you get away with something, such as spinning the turtle 360 degrees in zero time while sampling sensors and teleporting across the maze does NOT mean it is OK to do. There are rules you'll need to obey later in the semester that enforce things like taking time to move, inability to go through walls, and other properties of physical embedded systems and robots. In each time tick you can do only ONE of: turn left, turn right, move forward. In each time tick you can only check the bump sensor ONCE in the direction the turtle is facing.
• The "Spaghetti Factor" is covered in a recorded lecture on Spaghetti Code. We recommend you watch that lecture BEFORE starting work on this project. Similarly, you should watch the lectures on code style before working on this project. It is even better if you complete the associated homeworks before the project; doing so will make your life easier.

Procedure:

1. Ensure that your ANDREWID_student_turtle.cpp in ~/catkin_ws/src/ece642rtle/student is a working version (solves the maze using either the left-hand rule or right-hand rule based on how you did on Project 2. Revert to a working version using the source control you set up, if need be. If you have to start with the initial code from Project 2 that's OK.
2. Download and print out a physical version of the Code style checklist (It's only one page.)
3. Go through the checklist and make changes to your code. Check the checkbox after you make the change. You can do this in any order you like, but before you check a box make sure that you've looked at all the code for compliance with that checkbox.
   • Note: You might or might not agree with all of these rules. The rules have been carefully selected based on past semester problems we've seen with student code to guide everyone to a reasonably consistent starting point for later project phases. Later in the semester you'll have much more flexibility. (In industry there is often a house style sheet that everyone has to conform to whether they like it or not. Consider this a microcosm of that type of environment.)
   • In some cases the rules might seem like overkill. This is because we want you to get some practice in particular techniques even if the case for using them is not compelling in such a short program. For example, while it is certainly possible to skip typedefs in some cases, we want you to use typedefs so you understand how they work. (Not everyone taking this course has used typedefs before.) In larger programs the case for them is far more compelling. So this is a way to keep the assignment size reasonable while still exposing you to the concepts we want you to see.
   • Note that per the grading rubric (be sure to look at that before you start!) you can skip a few rules if you run out of time or are unsure how to comply. You'll have to fix these later, so don't abuse this slack.
4. You are graded primarily on code style for this project (not on how your turtle behaves at runtime). However, in future projects, you will be asked to make sure that your turtle obeys the following rules. Deviate at your own risk -- you'll have to clean up any messes before the end of the course! If you change the functionality of your code, please keep these rules in mind (by 'Tick', we mean one call to studentMoveTurtle, or, in future projects, moveTurtle, which is one time tick in the turtle+maze simulation):
   • The turtle shall not move more than one adjacent square per call to tick.
   • The turtle shall rotate at most 90 degrees per tick.
   • The turtle shall either rotate or move, but not both in a single tick. (No movement at all is also valid.)
   • The turtle shall only move in the direction it is facing, which is in even multiples of 90 degree increments.
   • The turtle shall be facing the potential wall segment that it is calling bumped for. (The bump sensor is in the nose of the turtle.)
   • The turtle shall make at most one call to bumped per tick.
   • The turtle shall not move through walls.
   • The turtle shall stop when it solves the maze via reaching the end square.
5. Build and run your turtle using ./build_run_turtle.sh in the ~/catkin_ws/src/ece642rtle directory.
   • The rubric has points for correct build and execution. The turtle must solve the maze. It does NOT have to follow the rules above for full credit in this project. But it will eventually. So do your best. If you are violating a rule and not sure how to resolve, see TAs at office hours to get help now rather than at a deadline later where following the rules is mandatory.
6. In a text document, answer the following questions: (Generate text however is convenient and legible; hand-in will be Acrobat)
   • Your name. (If the writeups are printed out, the file name info is lost, so put your name and Andrew ID in the document text as well)
   • Q1. What was the Spaghetti Factor of the module with the highest SF? If any modules have an SF greater than 10, why?
     • Note that a "module" is a single procedure or subroutine, and each module has its own SF number.It is NOT necessarily all the code in a single .c file. Rather, each .c file will have an SF value for each module in that file.
     • Only count global variables referenced by the specific module when determinine that module's SF, even if there are other globals in the file.
     • You can count SF by hand if you like, or use a tool if you find it convenient to do so.
   • Q2. List the numbers of the checklist items that you had already attempted on Project 2.
   • Q3. Do you strongly disagree with any items on the checklist? Which ones, and why?
   • Q4. Is there anything important you think should be added to the checklist? Why?
   • Q5. You are permitted to not fix up to three checklist items. List zero through three items you skipped. ("none" if you didn't skip)
   • Q6. Would you change anything about Project 3? If so, what?

Handin checklist

1. A scan or photo (pdf preferred even if it is a converted photo; jpg and png accepted) of your completed checklist. Call this file p03_checklist_[FAMILYNAME]_[GivenName_[AndrewID]].___
2. Your modified student_turtle.cpp file. Call this file p03_ANDREWID_student_turtle.cpp.
3. Your answers to the questions. Call this file p03_questions_[FAMILYNAME]_[GivenName]_[AndrewID].pdf

Zip these three files and turn them in on Canvas as P03_[FAMILY NAME]_[Given name]_[Andrew ID].zip

Other requirements:

• The writeup shall be in a single acrobat file for ease of navigation.
• Fonts for all diagrams and text shall be rendered at no smaller than 10 point font. Smaller fonts will require a resubmission

Please do NOT put these files inside a subdirectory. When unzipped they should not have any directory associated with the file name, and should just unzip into the current directory. (The file name convention will retain whose work it is.)

The rubric for the project is found here. BE SURE to use the rubric to understand what is expected on this hand-in; there are many moving parts in this assignment!

Changelog:

• 8/15/2022: released