[webkit-dev] initializing protected variable in a subclass

[David Hyatt]

Make your base class constructor take the role as an argument.  Then  
the subclasses can just pass in the value they want to use to  
initialize it

e.g.,

AccessibilityObject(AccessibilityRole role)
: m_role(role)
{
}

and then in the subclass

AccessibilityImageMapLink()
: AccessibilityObject(WebCoreLinkRole)
{
}

Another option is to just forego the member variable storage and make  
a virtual function that returns the role.  That only works if the role  
can be determined from the subclasses though.

virtual AccessibilityRole role() const { return WebCoreLinkRole; }

Hope this helps,
dave
(hyatt at apple.com)

On Aug 3, 2009, at 5:51 PM, Chris Fleizach wrote:

>
> I have added
>
> protected:
>     AccessibilityRole m_role;
>
> to AccessibilityObject.h
>
> I want to initialize that variable in subclasses of  
> AccessibilityObject, like so
>
> AccessibilityImageMapLink::AccessibilityImageMapLink()
>     : m_role(WebCoreLinkRole)
>
> but the compiler says
>
>
> /Volumes/data/WebKit/WebCore/accessibility/ 
> AccessibilityImageMapLink.cpp:48: error: class  
> ‘WebCore::AccessibilityImageMapLink’ does not have any field named  
> ‘m_role’
>
> even though this works fine
>
> AccessibilityImageMapLink::AccessibilityImageMapLink()
> {
>     m_role = WebCoreLinkRole;
> }
>
> any tips?
>
> thanx
> _______________________________________________
> webkit-dev mailing list
> webkit-dev at lists.webkit.org
> http://lists.webkit.org/mailman/listinfo.cgi/webkit-dev

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