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List:       kde-devel
Subject:    Re: Problem with derived class function name the same as base class
From:       Malte Starostik <malte () kde ! org>
Date:       2002-06-29 19:46:41
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Am Saturday 29 June 2002 22:41 schrieb Stephen Allewell:
> I have a class 'Editor' that is derived from QScrollView.  QScrollView
> has the function
> QPoint contentsToViewport(const QPoint &p)  to convert content
> coordinates to viewport coordinates.
> I also require to convert a QRect so I wrote the function:
>
> QRect Editor::contentsToViewport(QRect &r) {
>   return
> QRect(contentsToViewport(r.topLeft()),contentsToViewport(r.bottomRight()));
> }
>
> but when compiling I get the error that there is no matching function
> for contentsToViewport(QPoint &) unless I explicitly use
> QScrollView::contentsToViewport(...) which then compiles and works as
> intended.
>
> I thought that it was possible to have different functions with the
> same name as long as the parameters where different.
>
> Anyone have any idea why this doesn't work?
Yes, a method in a derived class hides any method with the same name in the 
base class. You have two possibilities here:

class Base
{
public:
	void doStuff( const QPoint& );
};

// Either:
class Derived : public Base
{
public:
	void doStuff( const QPoint& p ) { Base::doStuff( p ); }
	void doStuff( const QRect& );
};

// Or, but doesn't work with older compilers:
class Derived : public Base
{
public:
	using Base::doStuff;
	void doStuff( const QRect& );
};


- -- 
Malte Starostik
PGP: 1024D/D2F3C787 [C138 2121 FAF3 410A 1C2A  27CD 5431 7745 D2F3 C787]
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