How to properly define attributes when inheriting (c++, OOP)?

Question

OOP

I have a defined class hierarchy.
I need to make it possible to pass through some objects and not through others.
I think that for this I need to add an attribute of the type to the base class:
bool obstacle = false;
And also the method:
bool isObstacle() {return obstacle}
After that, for example in Wall write:
bool obstacle = true;
But in this form it does not work. The isObstacle method still returns the value from the base class.
How to do it right?

Answer 1

You can do it like this for example:

#include <iostream>
#include <iomanip>
#include <memory>

class ISomeInterface
{
public:
  virtual bool isFoo() const noexcept = 0;
};

class Foo : public ISomeInterface
{
public: 
  bool isFoo() const noexcept override { return true; }
};

class Bar : public ISomeInterface
{
public: 
  bool isFoo() const noexcept override { return false; }
};

int main()
{
  // Or shared_ptr/make_shared
  std::unique_ptr<ISomeInterface> foo = std::make_unique<Foo>();
  std::cout << "Foo is Foo: " << std::boolalpha << foo->isFoo() << std::endl;
  
  // Or shared_ptr/make_shared
  std::unique_ptr<ISomeInterface> bar = std::make_unique<Bar>();
  std::cout << "Bar is Foo: " << std::boolalpha << bar->isFoo() << std::endl;
  
  return 0;
}

Well, in the methods it is not necessary to return just true / false, there can be any other variable.