Re: Decorator design pattern ( C++ )
Pallav singh wrote:
[code stripped to the minimum]
class Widget {
virtual void draw() = 0;
};
class TextField : public Widget { ... };
class Decorator : public Widget {
public:
Decorator( Widget* w ): wid(w) {}
void draw() {
wid->draw();
}
};
class BorderDecorator : public Decorator { ... };
int main( void ) {
Widget* aWidget = new BorderDecorator( new TextField( 80, 24 ));
aWidget->draw();
}
How does interface property changes here ?
Huh? I'm not sure what you mean here. What is the 'interface property'? And
once you define that and 'here', it should be trivial to define whether it
changes.
Is it Following RAII( Resource Acquisition is Order of
initialization ) principle of C++ ?
Sorry, but you got that abbreviation wrong, there is no 'order' in RAII.
Anyway, typically RAII is used in the meaning that the lifetime of a
resource or some other operation is bound to the scope of an object, using
constructor and destructor. Which constructors and destructors of automatic
objects are called in your example?
How are virtual function helping it ?
Just implement 'it' (whatever exactly 'it' is...) without them as an example
and you will have hands-on experience.
Note: I've been intentionally vague in some answers because your questions
smell like homework, and while I don't mind helping with homework, you
don't seem to show an effort in solving it yourself and I'm not supporting
this perceived lazy attitude.
Uli
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