CODEWITHSUNDEEP
c++c++11inheritanceconstructor
Zebrafish
Zebrafish

Reputation: 14434

How to initialize derived class members when using C++11 inheriting constructors?

There's something I don't understand about the new C++11 feature of inheriting the base class's constructors with:

using BaseClass::BaseClass;

I thought this was a handy feature, but now I have a derived class that has additional members, and it seems I have to rewrite the constructor if I want to initialise the derived class's members:

struct BaseClass
{
    BaseClass(char* name, int intVal, float floatVal) : name(name), intVal(intVal), floatVal(floatVal) {}
    char* name;
    int intVal;
    float floatVal;
};

struct DerivedClass : BaseClass
{
    using BaseClass::BaseClass;
    int additionalMember;
};

Do I have to manually rewrite the constructor and pass the values to the base's constructor, then initialise the additional member? 

struct DerivedClass : BaseClass
    {
        DerivedClass(char* name, int intVal, float floatVal) : BaseClass(name, intVal, floatVal), additionalMember(7) {}
        int additionalMember;
    };

If so, the use of this new feature of inheriting constructors seems really limited.

So do I have to rewrite the constructors each time?

Upvotes: 3

Views: 317

Answers (1)

Resurrection
Resurrection

Reputation: 4106

You could use default value:

struct DerivedClass : BaseClass
{
    using BaseClass::BaseClass;
    int additionalMember = 0;
};

However if you need the value passed from the user of your class you will have to provide the constructor for DerviedClass.

Upvotes: 3

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