Do’s and Don’ts of Style – [OLD FALL 2019] 15-104 • Introduction to Computing for Creative Practice

A great programmer makes their code clear, robust, efficient, and user-friendly.
Code needs to be clear so others can read and understand your code.
Code needs to be robust* to reduce the number of errors in your program.
Code needs to be efficient to reduce the cost of your code.
Code needs to be user-friendly so that people will want to use your program.

Here are some Do’s and Don’ts that will guide you to becoming a better programmer. Bad style will cost your grade so keep these in mind and think of your own as well.

DO:

Comment your code concisely
Give your variables and functions good names for clarity
End your phrases with semi-colons
Indent your code properly
Include your name, andrew ID, and section on the top of your code

DON’T:

Have more than 80 characters in a line.
Have dead code (code that does nothing, or commented out code)
Use meaningless variable names
Use magic numbers (numbers that come out of nowhere)
Add too many comments, or redundant comments.
Use tab characters – fix your editor to insert spaces instead of tabs.

Here is a comparison of good and terrible code. If you can’t differentiate the two, ask for assistance as soon as possible.

/*
 * Andrew Carnegie
 * andrew@andrew.cmu.edu
 * Section Z
 *
 * This program draws gray concentric circles.
 */

function setup() {
    createCanvas(600, 600); // Sets up the canvas size
    background(50); // background is dark gray
}

function draw() {
    // draw a 4-ringed circle in the center of the screen
    drawConcentric(width / 2, height / 2, width / 3, 4);
}

function drawConcentric(xLoc, yLoc, radius, numRings) {
    // Interate through numRings and draw circles of decreasing
    // size.
    for (i = 1; i <= numRings; i++) {
        ellipse(xLoc, yLoc, radius / i, radius / i);
    }
}

* Andrew Carnegie

* andrew@andrew.cmu.edu

* Section Z

* This program draws gray concentric circles.

function setup() {

createCanvas(600, 600); // Sets up the canvas size

background(50); // background is dark gray

}

function draw() {

// draw a 4-ringed circle in the center of the screen

drawConcentric(width / 2, height / 2, width / 3, 4);

}

function drawConcentric(xLoc, yLoc, radius, numRings) {

// Interate through numRings and draw circles of decreasing

// size.

for (i = 1; i <= numRings; i++) {

ellipse(xLoc, yLoc, radius / i, radius / i);

}

// Lol comments

function setup()
{
    createCanvas(600, 600);
 background(50);
 background(2);
    background(7);
}

function draw() {
    // draw a 4-ringed circle in the center of the screen
    Draw2(300, 300, 100, 4);
}

function Draw2(v1, v2, v3, v4) {
for (i=1; i<=numRings; i++) {
    ellipse(v1, v2, v3/ i, v3 / i)
}
}

function DRAWSOMETHING() {
rect(100, 100, 100, 100) // Lol rekt
}

// Lol comments

function setup()

{

createCanvas(600, 600);

background(50);

background(2);

background(7);

}

function draw() {

// draw a 4-ringed circle in the center of the screen

Draw2(300, 300, 100, 4);

}

function Draw2(v1, v2, v3, v4) {

for (i=1; i<=numRings; i++) {

ellipse(v1, v2, v3/ i, v3 / i)

}

function DRAWSOMETHING() {

rect(100, 100, 100, 100) // Lol rekt

}

*“Robust” is a great adjective that, when talking about software, has a fairly specific and technical meaning. Robust software is software that works without depending on many assumptions or conditions. A program that crashes when an expected file is not found is not robust. A program that reports the missing file, prompts the user to find the file, or presses on using reasonable default values is more robust.