C++ Constructor initialization list strangeness

Question

I have always been a good boy when writing my classes, prefixing all member variables with m_:

class Test {
    int m_int1;
    int m_int2;
public:
    Test(int          


        

Answer 1

Yes, it's valid. The names in the member initializer list are looked up in the context of the constructor's class so int1 finds the name of member variable.

The initializer expression is looked up in the context of the constructor itself so int1 finds the parameter which masks the member variables.

Answer 2

I imagine this works because you were using int1 in the initialiser list, and the only things you can initialise are member variables => it was in fact unambiguous which variable was being initialised.

Whether all C++ compilers would be this forgiving is another matter!

Answer 3

What you have done is standard C++. Only member variables or base classes may be initliazed in the initialization list, so the variable outside the paranthesis is unambiguous. Within the parenthesis, the typical scoping rules apply, and the members are overshadowed by the parameter names.

Answer 4

What you have done is normal. This kind of implementation avoids you from even using the 'this' pointer (in this case).

Answer 5

This is perfectly normal behavior. As AAT rightly pointed out, there is no ambiguity. The variables initialised by the list have to be class members. This is standard and works across all compliant compilers.

The only thing to remember while using a list like this is that a person who doesn't understand this kind of code may have to maintain it. There is nothing wrong with writing initialisation code like this as long as you know what you are doing.