Heckendorn’s Law

Heckendorn’s Law is based on a saying of the great Robert Heckendorn:

That is, don’t do this:

    ifstream in(filename);
    if (!in) {
        cerr << "Bad file\n";
        return 1;
    }

Imagine the frustration of the user who reads this uninformative message. Which file is bad? What was wrong with it? What was the file trying to do with the file? What program was running, anyway?

There’s always more information that you can provide:

• program name from argv[0]
• filename
• operation attempted (open for reading, open for writing, deletion, rename)
• failure code via strerror or perror