huntergregory/slogo_turtles

"Turtle" drawing app with command-line and mouse inputs. Customize the UI to include different animation controls.

SLogo - Team 5 - README

(Harry Ross, David Miron, Hunter Gregory, Carter Gay)

CS 308, Spring 2019

---

A development environment that helps users write SLogo programs.

Start Date: 2/14/19
End Date: 3/9/19
Hours worked: 150+

---

Roles:

Frontend - Carter Gay, Hunter Gregory
Backend - Harry Ross, David Miron

Resources:

Prof. Duvall & UTAs
Java Documentation

---

Starting the project:

src/control/src/main/Main.java -> This file will launch and initialize the application.

Testing files:

Backend: A main method in parser.CommandParser was used over the course of the project to test functionality of the parser without relying on the frontend.

Error handling: Our backend throws ParserExceptions if errors occur while parsing that the frontend then catches and handles by displaying in the command prompt. These errors include:

• Incorrect parameter count for non-grouped commands
• Unterminated list or group
• Empty input
• Overwriting a standard SLogo command with a user defined command (i.e. to fd)
• Bad command/variable/constant syntax, illegal characters
• A command that requires a list as a parameter is given something else

Certain errors are accounted for and avoided within the parser itself. These include:

• Uneven parameter count for grouping command -> pads extra parameter slots with 0's (i.e. ( goto 3 4 5 ) becomes ( goto 3 4 5 0 ) when executed)
• Undefined commands and variables -> returns 0
• A group with the first command having no parameters ignores the rest of the group without error, and the rest of the group executes as a list.

Data/Resource files:

• Backend - No external resources.

• State Manager - Language files and Command Information, including number of parameters and translated Class names for reflection, list of Commands that support multiple inputs for grouping.

  • Format of language properties files:
    StandardizedCommandName = entered input (lower-case)
    ex. Forward = forward|fd
    (separated by lines for each command)
  • Format of Command Information file:
    StandardizedCommandName=command.class.name:#params ex. Sum=math_commands.SumCommand:2
    (separated by lines for each command)
  • Format of Multiple Input Enabled properties file:
    Command class names separated by line

• Frontend - CSS stylesheet, turtle images, and properties files for features

• Control - CSS stylesheet

Using the program:

• Click "PARSE" button to run commands
• Use various on-screen controls to manipulate aspects of the environment
• Click on the File menu button to
  • create a new workspace tab
  • load a file into the command terminal text display
• Click on the Customize... menu button to add features and choose which side to put them on (unique to each workspace).

Assumptions:

• Backend

  • Variable scope - It was not made clear in the assignment description if variables should have scope within subroutines. We chose to make all variables global for simplicity.

  • Parameter types - Commands that require a list as a parameter will not execute if given any other type of input. For example, dotimes [ :a 5 ] fd 50 will not execute since fd 50 is not in the form of a list.

  • Grouping - Grouping commands are classified in two categories: sequential and multi-input based on how they should intuitively act with many parameters. For example, commands like ( sum 1 2 3 4 5 ) pass a group of parameters to a SumCommand object whereas commands like ( fd 1 2 3 4 5 ) execute sequential forward commands. User defined commands always are executed sequentially when placed in groups. Commands with no parameters ignore everything inside the group after the command itself without giving an error. The rest of the group instead gets executed as a list.

• Frontend

  • Assumes pen features should be applied to all previously drawn lines instead of strictly newly drawn ones.
    • e.g. changing the pen color or line stroke affects every old line
  • Assumes turtle display will remain a fixed size

Missing features:

• Save/load functionality not implemented for turtle state
• No undo functionality (challenge feature)
• UI does not allow for editing user defined variables outside of commands
• Not possible to automatically update variables or user commands views with current design - must use refresh button
• Turtles can be shapes too, but switching between shapes and images is not incorporated currently

Known bugs:

• Background color cannot be set to first palette in list
• Background color resets when certain areas of the workspace are clicked

Extra features:

• Grouping was added from the "Challenging Extensions" list
• The option was implemented to load a text file into the workspace.
• A line stroke selector was added for the pen.
• Animation was added from the "Challenging Extensions" list

Assignment impressions:

Harry - Many of the design specifications for the backend were left frustratingly ambiguous. (i.e. which types of errors to check for, variable scope, if commands should accept normal variables as parameters when they were expecting lists, etc.) I'm unsure whether or not this was intentional, but making these points clearer from the start, even if that meant telling us that areas of the design were intentionally ambiguous, would have avoided confusion. Hunter - I enjoyed this project, and especially seeing it come together at the end. I was unclear of what the frontend api should be at first, and I would have preferred talking more about APIs and maybe examples of frontend APIs in class.