Error: "Function" is not a Non static data member or base class of "Class"

Question

I have the Component class implemented on my code and works fine

namespace GUI {
  class Component: public sf::Drawable, public sf::Transformable, private sf::NonCopyable {
    public:
    //Variables
  };
}

and also the book I'm studying asks me to implement another class called Container in the GUI namespace

Container::Container(): mChildren(), mSelectedChild(-1) {
    
}

void Container::pack(Component::Ptr component) {
  mChildren.push_back(component);
  if (!hasSelection() && component -> isSelectable())
    select(mChildren.size() - 1);
}

bool Container::isSelectable() const {
  return false;
}

What I don't get is the way he is implementing the class, which is giving me the syntax error in the title of the post:

Error: mChildren is not a Nonstatic data member or a base class of class GUI::Container.

I tried the further code:

class Container {
  Container::Container(): mChildren(), mSelectedChild(-1) {}
  void Container::pack(Component::Ptr component) {
    mChildren.push_back(component);
    if (!hasSelection() && component -> isSelectable())
      select(mChildren.size() - 1);
  }
  
  bool Container::isSelectable() const {
    return false;
  }
};

But I'm still getting syntax errors. What exactly is wrong and what should I read regarding this subject?

Note: I also read C++ guideline books but I didn't find the answer there cause I probably don't know how to refer to this problem.

Well, what *is* `mChildren`? Where do you declare/define it? — us2012, Sep 10 '13 at 20:59

score 7 · Accepted Answer · edited May 23 '17 at 12:16

7

When you define your methods inside your class declaration, you can't use the :: scope resolution operator.

Also your methods should probably in public. And finally you have to be sure that your mChildren member is correctly define.

class Container
{
    // ...

public:
    Container()
//  ^^
       : mChildren()
       , mSelectedChild(-1)
    {
    }
    void pack(Component::Ptr component)
//       ^^
    {
         // ...
    }
    bool isSelectable() const
//       ^^
    {
        // ...
    }

private:
    std::vector<Component::Ptr> mChildren;   // Example of a definition of mChildren
    //          ^^^^^^^^^^^^^^ replace with the good type

};

edited May 23 '17 at 12:16

Community

1
1

answered Sep 10 '13 at 21:00

Pierre Fourgeaud

14,290
1
38
62

So, components hasnt no methods at all, its calling from namespace sf - thats why it needs the colons right? – Victor Oliveira Sep 10 '13 at 21:05
@PierreFourgeaud in fact ou **can't** use the scope resolution. – brunocodutra Sep 10 '13 at 21:06
@VictorOliveira `Component` seems to inherits some methods from `sf::Drawable`, `sf::Transformable` and `sf::NonCopyable`. The `::` are used here to indicate some classes in the namespace `sf`. Your class `Component` seems correct. – Pierre Fourgeaud Sep 10 '13 at 21:09
@brunocodutra You are right, I changed my first lines. Thanks for your comment ! – Pierre Fourgeaud Sep 10 '13 at 21:10
@PierreFourgeaud its correct, works fine, but I couldnt solve the problem yet from the class Container..I cant see on the book any declaration from mChildren, Im completely lost...the syntax u provide me now recognize its as a class Container, but I still confront the problem about the mChildren =/ – Victor Oliveira Sep 10 '13 at 21:12
@VictorOliveira Look at [**this article**](http://stackoverflow.com/questions/9338217/why-does-c-need-the-scope-resolution-operator) to understand the use of `::`. – Pierre Fourgeaud Sep 10 '13 at 21:12
@VictorOliveira Is `Container` inheriting from another `class` in your book ? It seems this is the error here. – Pierre Fourgeaud Sep 10 '13 at 21:13
@PierreFourgeaud so mchildren is a method from container? – Victor Oliveira Sep 10 '13 at 21:18
1

@VictorOliveira No, I think that `mChildren` could be an attribute (do not mix method and attribute) of an inheriting `class`. But in the sample code I gave you, `mChildren` is an attribute of `Container`. – Pierre Fourgeaud Sep 10 '13 at 21:23

@PierreFourgeaud Yes, I entered with the code you gave

private:
    std::vector mChildren; but its weird cos on the book he doenst speak a **** about this mChildren as an Attribute, how did you guess this?

– Victor Oliveira Sep 10 '13 at 21:26

1

@VictorOliveira Some people uses `m` as a prefix for member. Also you are using it in the [*member-initialization-list*](http://en.cppreference.com/w/cpp/language/initializer_list) used to initialized members(but not only). What is the book where you found this class ? – Pierre Fourgeaud Sep 10 '13 at 21:31
@PierreFourgeaud It comes from SFML Game Development - Chapter 6 [Menus]; Im trying to learn C++ mean time I learn about game dev..I have some knowledge in C++ to move on, but no to specific, If I try to learn only C++ without a purpose I get bored, with Java wasnt so hard =/ – Victor Oliveira Sep 10 '13 at 21:34
1

@VictorOliveira Actually it seems the class declaration looks like this: https://github.com/LaurentGomila/SFML-Game-Development-Book/blob/master/06_Menus/Include/Book/Container.hpp. [Here](http://www.cplusplus.com/doc/tutorial/) are some resources about C++. (My guess about the `mChildren` member was right :) ) – Pierre Fourgeaud Sep 10 '13 at 21:38

score 0 · Answer 2 · answered Sep 10 '13 at 21:05

0

From this code you are using mChildren, but it is not defined in your Container class. What is mChildren supposed to be?

If it is a vector of Component::Ptr you need to define it in your class.

std::vector<Component::Ptr>mChildren;

answered Sep 10 '13 at 21:05

bruvel

396
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6

I'm not sure about what should be, 'cause in futher pages or previous I can't see references about it, but I will look for cos this is really weird – Victor Oliveira Sep 10 '13 at 21:07

score 0 · Answer 3 · answered Sep 10 '13 at 21:24

0

Why are you initializing mChildren in the constructor initialization list? More specifically what is this call mChildren() doing? Try removing that call and see what happens.

answered Sep 10 '13 at 21:24

ArmenB

2,125
3
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Error: "Function" is not a Non static data member or base class of "Class"

3 Answers3