== Auszug aus Steven Schveighoffer ([email protected])'s Artikel
> On Fri, 11 Feb 2011 15:40:18 -0500, %u <[email protected]> wrote:
> > Hello,
> >
> > I've a problem with my class inheritance. I have class called
Texture
> > which implements the interface IDrawable and the abstract class
> > APickable.
> > The Texture-class contains 3 members which looks like this:
> >
> > GLuint pTextureID;
> >
> > Size pSize1, pSize2;
> >
> > Finally... my Texture-class looks like:
> >
> > class Texture : APickable, IDrawable {
> > protected {
> > GLuint pTextureID;
> > Size pSize, pAnoutherSize;
> > }
> > }
> >
> > now... I have a second class called Animation which looks like
this:
> >
> > class Animation : Texture {
> > private {
> > Texture[] pFrames;
> > }
> > public {
> > this(string file, string[] paths...) {
> > super(file);
> > pFrames ~= this;
> > foreach(string cur; paths) {
> > pFrames ~= new Texture(cur);
> > }
> > }
> >
> > Size getSize() {
> > return pFrames[0].pSize;
> > }
> > }
> > }
> >
> > As I know, pFrames[0].pSize can be called... pSize in the Texture-
> > class is marked as protected, but I get the following error:
> >
> > Error: class Texture member pSize is not accessible.
> >
> > When I mark the protected members of the Texture-class as public,
it
> > works (should be clear), but why do I get this error when mark
them
> > as protected?
> >
> > I hope anyone can help to solve the problem.
> protected means you cannot access it outside the *instance*. The
pFrames
> array references *other instances* of Texture, so they are not
accessible.
> http://www.digitalmars.com/d/2.0/attribute.html#ProtectionAttribute
> "If accessing a protected instance member through a derived class
member
> function, that member can only be accessed for the object instance
which
> is the ‘this’ object for the member function call."
> -Steve
Thanks, but what about the following:
import std.stdio : writeln;
class a {
public this(int v) {
myVar = v;
}
protected int myVar;
}
class b : a {
private a[] moreInstances;
this(int v, int[] vars...) {
super(v);
moreInstances ~= this;
foreach(int cur; vars) {
moreInstances ~= new a(cur);
}
}
int getVar() {
return moreInstances[1].myVar;
}
}
void main(string[] args) {
b exp = new b(0, 1, 2);
writeln(exp.getVar());
}
This compiles fine and prints the number 1. myVar is also protected
in class a, I also call myVar in the getVar()-method of class b.
