Principle of Least Astonishment

The Principle of Least Astonishment (also known as the WTF principle) states that "People are part of the system. The design should match the user's experience, expectations, and mental models."

Note

Wikipedia, Principle of least astonishment: https://en.wikipedia.org/wiki/Principle_of_least_astonishment.

The choice of least surprising behavior depends on the expected audience and, hence, on the context.

We are software developers, so the principle says that we shouldn't mislead the developers who will work on the code in the future with names that are not coherent with the behavior inside the constructs.

For example:

int Multiply(int a, int b)
{
  return a + b;
}
int SaveFile(string filename, string text)
{
  Console.WriteLine(text);
}
public class SomethingFactory {
  //returning void???? for a factory????
  public void DoSomething()
  {
    ...