Protecting you from danger

One of the interesting features of Scala is the trait construct. In Java you have interfaces, a stripped down class that lets you express the requirements for classes that implement it to have a given … interface. Just to keep this from an OO perspective – in a certain system all MovableObjects, must expose an interface to retrieve, say, position, speed and acceleration:

interface MovableObject {
    Point getPosition();
    Vector getSpeed();
    Vector getAcceleration();
}

class Rocket implements MovableObject {
    public Point getPosition() {
        return m_position;
    }

    public Vector getSpeed() {
        return m_speed;
    }

    public Vector getAcceleration() {
        return m_acceleration;
    }
    private Point m_position;
    private Vector m_speed;
    private Vector m_acceleration;
}

In Java the interface has no implementation part, just a list of methods that heir(s) must implement. This is a way to mitigate the lack of multiple inheritance in the Java language – a class can inherit at most from a single base class, but can implement as many interfaces as needed.

Scala traits are different in the sense they can provide an implementation part and fields. Now that I read the wikipedia definition, it looks like that traits are a bit more mathematically sound than interfaces (that’s what you can expect in functional language). Anyway, in plain English, traits are very close to C++ base classes (with some additions that is stuff for another blog post) in the sense that you can both require interface and provide common functionality.

Read moreProtecting you from danger

Java vs. C++, last call

Well, I dragged this for too long. Now I have to pick the language for the next project. My language of choice is C++, but there are some serious motivation for using Java, one is that all of the junior programmers involved has some experience of Java, another is that middle management is biased toward Java. So, I can still chose C++, but I have to put forward strong and sound engineering reasons. Also because this can become a little … political. I mean – should the project be late for “natural” development reason, or whatever other reason, I don’t want to be blamed because I decided for a language perceived as complicated and rough.
The application isn’t going to need machoFlops or be resource intensive, therefore performance-wise there is no reason to avoid Java.
Java has a thorough and complete library, quite homogeneous even if not always well designed.
I consider C++ to be more flexible and expressive, but is there a more demonstrable software engineering property of C++ that I can use in my argumentations to favor the choice of this language?
(Or conversely is there any demonstrable advantage of Java the could convince me to switch my language of choice).

C++ To Gui or Not To Gui?

One of the most missing feature of the C and C++ standards is, at least for us everyday programmers, the standardisation of the GUI. What a bless could be a single approach to the GUI programming. Tools companies may focus their efforts to provide wonderful tools, programmers could stop wasting time in #ifdeffing around, and so on. Anyway looking at Java language maybe that ISO/ANSI committee were not so wrong in taking such a conservative approach. At only some 10 years after the language debut, Java, although strictly controlled by Sun, has 4 different (and incompatible) GUI toolkits (JWT, AWT, Swing, SWT) plus the J2ME GUI interface.