CODEWITHSUNDEEP
c++classattributesoption-type
Phann
Phann

Reputation: 1337

How to implement optional attributes in a class

I have a class MyClass mainly based on one member Attribute. What is the best possibility to implement optional members Optional1 and Optional2 into the class definition. The idea is that in some cases there is more information about the MyClass-object which should be added to it.

class MyClass {
private:
    double Attribute;
    //double Optional1; //that's what I want to implement
    //double Optional2; //that's what I want to implement
public:
    MyClass(Attribute);
    void setAttribute(double);
    //void setOptional1(double);
    //...
};

I think there is nothing like a really optional member in a class, so I probably have to deal with default values in the constructor. Something like

MyClass(Attribute, Optional1 = -1, Optional2 = -1)

If -1 is never set in a normal case, I know for sure that Optional1 and/or Optional2 "is not set". If it is different from -1, I know it has an intented value.

However, this approach seems to be a bit ugly and I wonder if there is some better way.

Upvotes: 2

Views: 1254

Answers (1)

lorro
lorro

Reputation: 10880

You might be searching for std::optional<> if it's runtime-optional or bool template parameter(s) if it's compile-time optional. But, first and foremost, verify your design: are we talking about the same class and not a class hierarchy?

Upvotes: 2

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