Ten commandments of Programming

I came across the Ten commandments of Programming while looking at a question on StackOverflow and I can’t believe I have not seen these before. I think every developer, lead, architect, dba, pm, whoever should print this out! 😎

  1. Understand and accept that you will make mistakes. The point is to find them early, before they make it into production. Fortunately, except for the few of us developing rocket guidance software at JPL, mistakes are rarely fatal in our industry, so we can, and should, learn, laugh, and move on.
  2. You are not your code. Remember that the entire point of a review is to find problems, and problems will be found. Don’t take it personally when one is uncovered.
  3. No matter how much “karate” you know, someone else will always know more. Such an individual can teach you some new moves if you ask. Seek and accept input from others, especially when you think it’s not needed.
  4. Don’t rewrite code without consultation. There’s a fine line between “fixing code” and “rewriting code.” Know the difference, and pursue stylistic changes within the framework of a code review, not as a lone enforcer.
  5. Treat people who know less than you with respect, deference, and patience. Nontechnical people who deal with developers on a regular basis almost universally hold the opinion that we are prima donnas at best and crybabies at worst. Don’t reinforce this stereotype with anger and impatience.
  6. The only constant in the world is change. Be open to it and accept it with a smile. Look at each change to your requirements, platform, or tool as a new challenge, not as some serious inconvenience to be fought.
  7. The only true authority stems from knowledge, not from position. Knowledge engenders authority, and authority engenders respect—so if you want respect in an egoless environment, cultivate knowledge.
  8. Fight for what you believe, but gracefully accept defeat. Understand that sometimes your ideas will be overruled. Even if you do turn out to be right, don’t take revenge or say, “I told you so” more than a few times at most, and don’t make your dearly departed idea a martyr or rallying cry.
  9. Don’t be “the guy in the room.” Don’t be the guy coding in the dark office emerging only to buy cola. The guy in the room is out of touch, out of sight, and out of control and has no place in an open, collaborative environment.
  10. Critique code instead of people—be kind to the coder, not to the code.As much as possible, make all of your comments positive and oriented to improving the code. Relate comments to local standards, program specs, increased performance, etc.

Copying strings in C++

Here is a good example on why either you love C++ or hate it with such terse expression oriented code; I think its pretty cool.

If you want to copy one string to another, one option can be something like this.

void mycopy(char *p, char *q) {
	int len = strlen(q);

	for(int i=0; i<=len; i++)
		p[i] = q[i];
}

However this achieves the same thing as above and is more efficient:

void mycopy(char *p, char *q) {
	while(*p++ = *q++);
}

Of course why would you write your own version when you have standard string copy fundtion strcpy in <string.h>

‘QPainter painter’ has initialiser but incomplete type

If you ever got an error something like [some-class] has initialiser but incomplete type, it basically means the compiler cannot understand the type and you need to add the include for it.

QPixmap pixmap(20,10);
pixmap.fill(Qt::white);

QPainter painter(&pixmap);
QPen pen(Qt::blue);

Take the code snipped above when you compile it you might get an error something along the lines of the following for line 4.

‘QPainter painter’ has initialiser but incomplete type

To fix this you need to include the header file where QPainter is defined. The updated code looks like:

#include <qpainter.h>

QPixmap pixmap(20,10);
pixmap.fill(Qt::white);

QPainter painter(&pixmap);
QPen pen(Qt::blue);

Making sense of primary-expression error

If you are new to C++ then some of the compiler errors can be a bit confusing and daunting at first. For example if the compiler given you an expected primary-expression error (e.g. expected primary-expression before ‘.’ token), at face value it does not make sense.

void RGBViewer::accept() {
	QMessageBox::information(this, "Button Clicked", "You clicked OK", QMessageBox::Ok);

	QColor color = QColor(Ui_RGBViewerClass.spinBoxRed->value(),
			Ui_RGBViewerClass.spinBoxGreen->value(),
			Ui_RGBViewerClass.spinBoxBlue->value(),
			255);

	qDebug() << color;

	QBrush brush(color);
	brush.setStyle(Qt::SolidPattern);
	ui.graphicsView->setBackgroundBrush(brush);
	ui.graphicsView->backgroundBrush();
}

When I compile the above code snippet, I get the following error from the compiler:

rgbviewer.cpp: In member function ‘virtual void RGBViewer::accept()’:
rgbviewer.cpp:19: error: expected primary-expression before ‘(’ token
rgbviewer.cpp:19: error: expected primary-expression before ‘.’ token
rgbviewer.cpp:20: error: expected primary-expression before ‘.’ token
rgbviewer.cpp:21: error: expected primary-expression before ‘.’ token

All this means is that I need to initialize the type ‘Ui_RGBViewerClass’ as the compiler does not understand it. In other words, I need to use a new.

Here is the ‘fixed’ version below of the same code snippet.

Ui::RGBViewerClass ui; //Defined in the header; shown here for completness

void RGBViewer::accept() {
	QMessageBox::information(this, "Button Clicked", "You clicked OK", QMessageBox::Ok);

	QColor color = QColor(ui.spinBoxRed->value(),
			ui.spinBoxGreen->value(),
			ui.spinBoxBlue->value(),
			255);

	qDebug() << color;

	QBrush brush(color);
	brush.setStyle(Qt::SolidPattern);
	ui.graphicsView->setBackgroundBrush(brush);
	ui.graphicsView->backgroundBrush();
}

Sandbox is Up!

As promised earlier, the Sanbox is up – go give it a whirl and let me know your thoughts. Also the code and release build of the World Clock are up there. Check it out and let me know what you think of it and also any bugs and feature enhancements you would like to see.