Question

Suppose I have a class like this:

class MyClass {
    private:
        vector<MyOtherClass> myMember;
    public:
        MyClass(const YetAnotherClass& myCollection);
}

MyClass::MyClass(const YetAnotherClass& myCollection) {
    myMember = convert(myCollection);
}

Or, in other words, I have a class with a member that’s some other data converted to be used afterwards.

Now, the weffc++ flag helps catch some stupid mistakes and makes the compiler a lot more helpful. At the same time, I like Wextra because it forces me to fix my mistakes.

The problem is that the code doesn’t compile (“MyClass::myMember should be initialized in the member initialization list”) and I dunno how to get around it. I guess I could make the myMember a pointer and set it to NULL but I’d rather not do that. I also can’t find a way to disable the warning, though I’m not sure that would be a good idea either.

I’m using GCC 4.5.2, if it makes any difference.

So, how should I go about this?

Answer 1

You’re not actually using a member initialization list in this instance.

To use the member initialization list in this case, your constructor implementation would look like this:

MyClass::MyClass(const YetAnotherClass &myCollection) 
: myMember(convert(myCollection))
{
}

The member initialization list is a comma separated list of member variables after the colon. Multiple member initializations would look something like this:

class MyClass
{
public:
    MyClass();

private:
    SomeType someMember;
    SomeOtherType someOtherMember;
    AnotherType anotherMember;
};

MyClass::MyClass() :
    someMember(a),
    someOtherMember(b),
    anotherMember(5)
{}