Hi list,
I'm wondering whether it's possible to pass construction parameters to
a superclass constructor from a subclass constructior. Knowing that
you're supposed to ``chain up to the superclass constructor, the
absolutely first thing you do'', I'm a little scared to tamper with
the `construct_properties' before chaining up.
Also, I'm unsure as to what should happen if the user specifies their
own value for some of the parameters that I want to pass
automatically. Am I ``overriding'' the parameters, or am I just
defining ``intelligent defaults'' for them?
C++ and Java, for example -- and in fact any other object-oriented
languages I can think of -- do not have this problem. In those
languages, creating a subclass can only be done through the use of a
well-defined subclass constructor interface.
class Parent {
Resource resource;
Parent(int size) {
resource = new Resource(size);
}
}
class Child extends Parent {
private static final int UNIT_SIZE = 42;
Child(int n_units) {
super(n_units * UNIT_SIZE);
}
}
With this API, you can't create a Child while also specifying the
construction parameter of Parent. The only way to create a Child is
by doing this:
Child child = new Child(123);
With GObject, you could do this:
Child *child = g_object_new (TYPE_CHILD,
"n-units", 123,
"size", 456,
NULL);
Any thoughts?
Regards,
--
Daniel Brockman
drlion@xxxxxxxxxxxx
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