std::is_abstract
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<metanoindex/>
<tbody> </tbody>| Definido no cabeçalho <type_traits>
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template< class T > struct is_abstract; |
(desde C++11) | |
Se
T é uma classe abstrata (ou seja, uma classe que declara ou herda pelo menos uma função virtual pura), fornece o membro constante value true igual. Para qualquer outro tipo, é value false.Original:
If
T is an abstract class (that is, a class that declares or inherits at least one pure virtual function), provides the member constant value equal true. For any other type, value is false.The text has been machine-translated via Google Translate.
You can help to correct and verify the translation. Click here for instructions.
You can help to correct and verify the translation. Click here for instructions.
Herdado de std::integral_constant
Member constants
value [estática] |
true se T is an abstract class type , false contrário Original: true if T is an abstract class type , false otherwise The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (membro estático público constante) |
Member functions
operator bool |
converte o objeto em bool, retorna value Original: converts the object to bool, returns value The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (função pública membro) |
Member types
Tipo
Original: Type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. |
Definition |
value_type
|
bool
|
type
|
std::integral_constant<bool, value>
|
Notas
Classes abstratas só podem ser usados como classes base, nenhum objeto de um tipo de classe abstrata pode ser criado, exceto na forma de sub-objetos da classe base.
Original:
Abstract classes may only be used as base classes; no objects of an abstract class type can be created except in form of base class subobjects.
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Uma classe abstrata pode ser derivada de uma classe que não é abstrato se uma função virtual pura substitui uma função virtual que não é puro.
Original:
An abstract class may be derived from a class that is not abstract if a pure virtual function overrides a virtual function that is not pure.
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Exemplo
#include <iostream>
#include <type_traits>
struct A {
int m;
};
struct B {
virtual void foo();
};
struct C {
virtual void foo() = 0;
};
struct D : C {};
int main()
{
std::cout << std::boolalpha;
std::cout << std::is_abstract<A>::value << '\n';
std::cout << std::is_abstract<B>::value << '\n';
std::cout << std::is_abstract<C>::value << '\n';
std::cout << std::is_abstract<D>::value << '\n';
}
Saída:
false
false
true
true
Veja também
(C++11) |
checks if a type is a class type (but not union type) (modelo de classe) |
(C++11) |
verifica se um tipo é o tipo de classe polimórfica Original: checks if a type is polymorphic class type The text has been machine-translated via Google Translate. You can help to correct and verify the translation. Click here for instructions. (modelo de classe) |