C++ inherit constructor

Question

I have a class, Tile, that has a constructor with parameters of a Color object:

class Tile
{
public:
    static const int size = 32;

    Tile();
    Tile(Color &color);

    void render(int x, int y);

    Color getColor();

    ~Tile();
private:
    Color _color;
};

Then I have a subclass, TileGrass, which inherits Tile:

class TileGrass : public Tile
{
public:
    TileGrass();
    ~TileGrass();
};

Now the issue is that the TileGrass needs to inherit the Tile constructor with the Color parameters. But, the TileGrass object already knows what color it needs to give to the superclass, so I don't want to have to pass in a Color object when creating a new TileGrass object. In Java I can do something like this:

public class TileGrass extends Tile {

public TileGrass() {
    super(color object);
}
}

How can I do something like this in C++?

In C++(11) inheriting constructors means being able to call a constructor of the base class to build a derived object. Here you just want to call a specific base constructor inside the derived constructor, pretty standard thing... — DarioP, Jun 30 '14 at 19:12
@user3316633: Also, please note that `~Tile()` should be declared virtual. See [this question](http://stackoverflow.com/questions/270917/why-should-i-declare-a-virtual-destructor-for-an-abstract-class-in-c) for details on why. — Edward, Jun 30 '14 at 19:18

score 9 · Answer 1 · answered Jun 30 '14 at 19:03

9

Just call the relevant base class constructor in the initialization list:

class TileGrass : public Tile
{
 public:
  TileGrass() : Tile(some_color) 
  {
    // ....
  }

  ~TileGrass();
};

answered Jun 30 '14 at 19:03

juanchopanza

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I believe this is actually called inheriting constructors in the ISO standard as well. – The Floating Brain Jun 30 '14 at 19:16
1

@TheFloatingBrain Inheriting constructors refers to a different thing. For example, `using Tile::Tile` would let you construct `TileGrass t(some_color);` without having to declare and define `TileGrass(Color&)`. – juanchopanza Jun 30 '14 at 19:19
1

@TheFloatingBrain See [Inheriting constructors](http://stackoverflow.com/questions/347358/inheriting-constructors) – Ivan Aksamentov - Drop Jun 30 '14 at 19:20
@Drop I forgot about that, thank you :-) – The Floating Brain Jun 30 '14 at 19:24
@juanchopanza Thanks I kinda forgot about that :-) – The Floating Brain Jun 30 '14 at 19:25

C++ inherit constructor

1 Answers1