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Asked: 2020-12-07 13:59:20 +0800 CST 2020-12-07 13:59:20 +0800 CST

Why is this method not inherited?

  • 772

Given the following code:

class Padre
{
  public:
    int func()
    { return 0; }

    int func2()
    { return 0; }
};

class Hija
  : public Padre
{
  public:
    int func(int param)
    { return param; }
};

int main()
{
  Hija clase;

  std::cout << clase.func(); << std::endl; // ERROR
  std::cout << clase.func(5); << std::endl; // OK
  std::cout << clase.func2(); << std::endl; // OK
}

Why does the method funcof the parent class not exist in the child class despite the fact that the inheritance is public, and yet it func2does?

c++

1 Answers

  1. Best Answer

    Because you are inadvertently invoking the Name Hidingc++ call feature , from section § 3.3.10 of the current standard for :c++

    Name Hiding: A name will be hidden by an explicit declaration with the same name in a nested declarative region or in derived classes.

    Note that doing this is considered bad practice as it is unintuitive and should be avoided. And it is not an error -since it is well stipulated in the standard- but rather a feature of the language.

    The correct solution would be to use different names for the methods.

    But if you have no other choice or just don't want to use different names there is another language feature to make it visible explicitly in the derived class.

    It is achieved usingusing

    class Hija
  : public Padre
{
  public:
    using Padre::func; // <-- puedes hacerla visible así.

    int func(int param)
    { return param; }
};

    Here you can see the program running after the fix.

    Note: Be aware that this will happen even if Hija::funcdeclared as private( see example ).

    • 13