Question

All the member variables and member functions in my class ClassA are static.

If a user is trying (by mistake) to create an object of this class, he receives a warning: ‘ClassA, local variable never referenced’, because all the functions are static, so this object is never referenced. So, I want to prevent the user from trying to create an object of this class.

Would it be enough to create a private default (no variables) constructor? Or do I have to also create private copy constructor and private assignment operator (to prevent using the default constructors)? And if I do have to create them too, maybe it would be better just to create some dummy pure virtual function instead, and this will prevent the user from creating an object?

Thank you

Answer 1

Like others said, a namespace is what you should use. If you want to stay with your class, create a class that has a private constructor, and derive from it, to make your intention obvious:

class NonConstructible {      NonConstructible(); };  class SuperUtils: NonConstructible {     static void foo();     // ...     static std::vector<int> globalIDs;     // ... }; 

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Ok, now let’s look into the namespace which are the one and only way to do this:

namespace SuperUtils {     void foo() {         // ....     }      std::vector<int> globalIDs; }; 

You can call that using SuperUtils::foo(); in both cases, but the namespace has the advantage that in a scope you can use the namespace declaration and directive to bring certain or all members into the current scope, so that you can reference them without using SuperUtils:::

void superFunction() {     using namespace SuperUtils;     foo(); } 

While generally that should be avoided, it can be helpful when the method is using exclusively much stuff from SuperUtils, which then can improve the readability of the code.