[Qt-interest] Library binary compatibility issue

[Giacomo S.]

Hi to all!

A question about binary compatibility issue in a library of mine:

class Reader
{
  ...
  protected:
	virtual void refresh(const TVariant&) = 0;
}

class Label : public QLabel, public Reader
{
	...
	protected:
		void refresh(const TVariant&) ; /* implement refresh */
}

Later on, I discovered that it would be useful for classes inheriting
Label to reimplement refresh() method.

Does changing refresh() into 

class Label : public QLabel, public Reader
{
	...
	protected:
	virtual void refresh(const TVariant&); /* make it virtual */
}

into Label class break binary compatibility for classes using the Label
object in the library??

I had a look at 

http://techbase.kde.org/Policies/Binary_Compatibility_Issues_With_C
++#The_Do.27s_and_Don.27ts

but did not found the case.

Thanks in advance.

Giacomo.

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