inheritance, pure virtual

[TheKedge]

Hello all,

I'd like to make a abstract base class with one pure virtual function. Let's say it looks like this:

class BuddyBase  : public QWidget
{
public:
	BuddyBase(QWidget* parent = 0);
	virtual ~BuddyBase();
public:
	virtual void update (QString text) = 0;

class BuddyBase  : public QWidget
{
public:
	BuddyBase(QWidget* parent = 0);
	virtual ~BuddyBase();
public:
	virtual void update (QString text) = 0;

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I'd like to inheirit this, making a class that (of course) implements its own update(). But, I'd like to have
update(double*), or, in some other case update(QVector), for instance.
How can I do it?

Do I have to declare
virtual void update(class <T>)=0;
or something?
Will this be ok with the inheiritance of QWidget?

thanks
Kev