I'm inheriting from multiple abstract base classes (2 to be exact).
In the inherited class I want to know if I can implement two pure
virtual methods (one from each base class) having the same name?
An example is worth a thousand words (Note: I didn't check syntax but
you will get this gist of it), so here it is ....
class Base1
{
virtual void action() = 0;
};
class Base2
{
virtual void action() = 0;
};
class Derived : public Base1, public Base2
{
/*How the heck do I implement both inherited "action" methods? I filled
in an idea here that I'm working on, but cannot seem to get it to
compile ...
*/
Base1::action() { /* do stuff */; } // does not work
Base2::action() { /* do stuff */; } // ditto
};
???
Thanks.
--John 6 2015
John wrote: class Base1 { virtual void action() = 0; };
class Base2 { virtual void action() = 0; };
class Derived : public Base1, public Base2 {
void action() { /* do stuff */; }
};
--
Pete Becker
Dinkumware, Ltd. ( http://www.dinkumware.com)
John wrote:
I'm inheriting from multiple abstract base classes (2 to be exact). In the inherited class I want to know if I can implement two pure virtual methods (one from each base class) having the same name?
An example is worth a thousand words (Note: I didn't check syntax but you will get this gist of it), so here it is ....
class Base1 { virtual void action() = 0; };
class Base2 { virtual void action() = 0; };
class Derived : public Base1, public Base2 { /*How the heck do I implement both inherited "action" methods?
Just the same as you do always:
virtual void action() { /* do stuff */ }
I filled in an idea here that I'm working on, but cannot seem to get it to compile ... */ Base1::action() { /* do stuff */; } // does not work Base2::action() { /* do stuff */; } // ditto };
???
Pete Becker <pe********@acm .org> wrote: John wrote: class Base1 { virtual void action() = 0; };
class Base2 { virtual void action() = 0; };
class Derived : public Base1, public Base2 {
void action() { /* do stuff */; }
};
Of course, this implies that the specification for both 'action()' methods
is identical or at least similar. This is not necessarily a given (although,
admittedly, likely for a function returning nothing and taking no parameter).
If both bases have different requirements on the implementation of the
function and/or a different return type, you have to use two auxiliary base
classes, each implementing one of the functions. I don't think that C++ has
a mechanism like e.g. C# which allows specification of the base class when
overriding a virtual function.
--
<mailto:di***** ******@yahoo.co m> <http://www.dietmar-kuehl.de/>
<http://www.contendix.c om> - Software Development & Consulting
Dietmar Kuehl posted: I don't think that C++ has a mechanism like e.g. C# which allows specification of the base class when overriding a virtual function.
class Base1 ...
class Base2 ...
class Derived : public Base1, public Base2 ...
int main()
{
Derived o;
o.Blah;
o.Base1::Blah() ;
o.Base2::Blah() ;
}
Or:
void Derived::Blah()
{
this->Base1::Blah( );
this->Base2::Blah( );
}
-JKop
JKop wrote: Dietmar Kuehl posted: I don't think that C++ has a mechanism like e.g. C# which allows specification of the base class when overriding a virtual function.
Note my statement: "... when *overriding* a virtual function." I'm aware and
didn't dispute the fact that you can use specification of a base class when
*calling* a virtual function (well, actually, any function).
class Base1 ... class Base2 ... class Derived : public Base1, public Base2 ...
int main() { Derived o; o.Blah; o.Base1::Blah() ; o.Base2::Blah() ; }
This is, however, calling a virtual function.
void Derived::Blah() { this->Base1::Blah( ); this->Base2::Blah( ); }
OK, this may be overriding a virtual function but you still cannot qualify
which virtual function is overridden which was what I was referring to,
e.g.:
struct Base1 { virtual int f() = 0; };
struct Base2 { virtual double f() = 0; };
struct Derived1: Base1, Base2 {
// how to define 'f()' here?
};
struct Aux1: Base1 { int f() { return 17; } };
struct Aux2: Base2 { double f() { return 3.14; } };
struct Derived2: Aux1, Aux2 {
// no need to define 'f()' here...
};
--
<mailto:di***** ******@yahoo.co m> <http://www.dietmar-kuehl.de/>
<http://www.contendix.c om> - Software Development & Consulting
* Dietmar Kuehl: I don't think that C++ has a mechanism like e.g. C# which allows specification of the base class when overriding a virtual function.
Right. Visual C++ has that as an extension. With some mysterious quirks...
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
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