auto_handle, classe

Gestion automatique des ressources, qui peut être utilisée pour incorporer un handle virtuel dans un type managé.

Syntaxe

template<typename _element_type>
ref class auto_handle;

Paramètres

_element_type
Type managé à incorporer.

Membres

Constructeurs publics

Méthodes publiques

Opérateurs publics

Spécifications

Fichier d’en-tête<msclr\auto_handle.h>

Namespace msclr

auto_handle::auto_handle

Constructeur auto_handle.

auto_handle();
auto_handle(
   _element_type ^ _ptr
);
auto_handle(
   auto_handle<_element_type> % _right
);
template<typename _other_type>
auto_handle(
   auto_handle<_other_type> % _right
);

Paramètres

_ptr
Objet à posséder.

_Droite
auto_handle existant.

Exemple

// msl_auto_handle_auto_handle.cpp
// compile with: /clr
#include "msclr\auto_handle.h"

using namespace System;
using namespace msclr;
ref class RefClassA {
protected:
   String^ m_s;
public:
   RefClassA(String^ s) : m_s(s) {
      Console::WriteLine( "in RefClassA constructor: " + m_s );
   }
   ~RefClassA() {
      Console::WriteLine( "in RefClassA destructor: " + m_s );
   }

   virtual void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }
};

ref class RefClassB : RefClassA {
public:
   RefClassB( String^ s ) : RefClassA( s ) {}
   virtual void PrintHello() new {
      Console::WriteLine( "Hello from {0} B!", m_s );
   }
};

int main()
{
   {
      auto_handle<RefClassA> a(gcnew RefClassA( "first" ) );
      a->PrintHello();
   }

   {
      auto_handle<RefClassB> b(gcnew RefClassB( "second" ) );
      b->PrintHello();
      auto_handle<RefClassA> a(b); //construct from derived type
      a->PrintHello();
      auto_handle<RefClassA> a2(a); //construct from same type
      a2->PrintHello();
   }

   Console::WriteLine("done");
}

in RefClassA constructor: first
Hello from first A!
in RefClassA destructor: first
in RefClassA constructor: second
Hello from second B!
Hello from second A!
Hello from second A!
in RefClassA destructor: second
done

auto_handle::~auto_handle

Destructeur auto_handle .

~auto_handle();

Notes

Le destructeur détruit également l’objet appartenant.

Exemple

// msl_auto_handle_dtor.cpp
// compile with: /clr
#include "msclr\auto_handle.h"

using namespace System;
using namespace msclr;

ref class ClassA {
public:
   ClassA() { Console::WriteLine( "ClassA constructor" ); }
   ~ClassA() { Console::WriteLine( "ClassA destructor" ); }
};

int main()
{
   // create a new scope for a:
   {
      auto_handle<ClassA> a = gcnew ClassA;
   }
   // a goes out of scope here, invoking its destructor
   // which in turns destructs the ClassA object.

   Console::WriteLine( "done" );
}

ClassA constructor
ClassA destructor
done

auto_handle::get

Obtient l’objet contenu.

_element_type ^ get();

Valeur retournée

Objet contenu.

Exemple

// msl_auto_handle_get.cpp
// compile with: /clr
#include "msclr\auto_handle.h"

using namespace System;
using namespace msclr;

ref class ClassA {
   String^ m_s;
public:
   ClassA( String^ s ) : m_s( s ){
      Console::WriteLine( "in ClassA constructor:" + m_s );
   }
   ~ClassA() {
      Console::WriteLine( "in ClassA destructor:" + m_s );
   }

   void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }
};

void PrintA( ClassA^ a ) {
   a->PrintHello();
}

int main() {
   auto_handle<ClassA> a = gcnew ClassA( "first" );
   a->PrintHello();

   ClassA^ a2 = a.get();
   a2->PrintHello();

   PrintA( a.get() );
}

in ClassA constructor:first
Hello from first A!
Hello from first A!
Hello from first A!
in ClassA destructor:first

auto_handle::release

Libère l’objet de auto_handle la gestion.

_element_type ^ release();

Valeur retournée

Objet libéré.

Exemple

// msl_auto_handle_release.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

ref class ClassA {
   String^ m_s;
public:
   ClassA( String^ s ) : m_s( s ) {
      Console::WriteLine( "ClassA constructor: " + m_s );
   }
   ~ClassA() {
      Console::WriteLine( "ClassA destructor: " + m_s );
   }

   void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }
};

int main()
{
   ClassA^ a;

   // create a new scope:
   {
      auto_handle<ClassA> agc1 = gcnew ClassA( "first" );
      auto_handle<ClassA> agc2 = gcnew ClassA( "second" );
      a = agc1.release();
   }
   // agc1 and agc2 go out of scope here

   a->PrintHello();

   Console::WriteLine( "done" );
}

ClassA constructor: first
ClassA constructor: second
ClassA destructor: second
Hello from first A!
done

auto_handle::reset

Détruisez l’objet détenu actuel et prenez éventuellement possession d’un nouvel objet.

void reset(
   _element_type ^ _new_ptr
);
void reset();

Paramètres

_new_ptr
(Facultatif) Nouvel objet.

Exemple

// msl_auto_handle_reset.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

ref class ClassA {
   String^ m_s;
public:
   ClassA( String^ s ) : m_s( s ) {
      Console::WriteLine( "ClassA constructor: " + m_s );
   }
   ~ClassA() {
      Console::WriteLine( "ClassA destructor: " + m_s );
   }

   void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }
};

int main()
{
   auto_handle<ClassA> agc1 = gcnew ClassA( "first" );
   agc1->PrintHello();

   ClassA^ ha = gcnew ClassA( "second" );
   agc1.reset( ha ); // release first object, reference second
   agc1->PrintHello();

   agc1.reset(); // release second object, set to nullptr

   Console::WriteLine( "done" );
}

ClassA constructor: first
Hello from first A!
ClassA constructor: second
ClassA destructor: first
Hello from second A!
ClassA destructor: second
done

auto_handle::swap

Échange des objets avec un autre auto_handle.

void swap(
   auto_handle<_element_type> % _right
);

Paramètres

_Droite
auto_handle Avec lequel échanger des objets.

Exemple

// msl_auto_handle_swap.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

int main() {
   auto_handle<String> s1 = "string one";
   auto_handle<String> s2 = "string two";

   Console::WriteLine( "s1 = '{0}', s2 = '{1}'",
      s1->ToString(), s2->ToString() );
   s1.swap( s2 );
   Console::WriteLine( "s1 = '{0}', s2 = '{1}'",
      s1->ToString(), s2->ToString() );
}

s1 = 'string one', s2 = 'string two'
s1 = 'string two', s2 = 'string one'

auto_handle::operator->

Opérateur d’accès membre.

_element_type ^ operator->();

Valeur retournée

Objet encapsulé par auto_handle.

Exemple

// msl_auto_handle_op_arrow.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

ref class ClassA {
protected:
   String^ m_s;
public:
   ClassA( String^ s ) : m_s( s ) {}

   virtual void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }

   int m_i;
};

int main() {
   auto_handle<ClassA> a( gcnew ClassA( "first" ) );
   a->PrintHello();

   a->m_i = 5;
   Console::WriteLine( "a->m_i = {0}", a->m_i );
}

Hello from first A!
a->m_i = 5

auto_handle::operator=

Opérateur d'assignation.

auto_handle<_element_type> % operator=(
   auto_handle<_element_type> % _right
);
template<typename _other_type>
auto_handle<_element_type> % operator=(
   auto_handle<_other_type> % _right
);

Paramètres

_Droite
à auto_handle affecter au fichier actif auto_handle.

Valeur retournée

Le courant auto_handle, maintenant propriétaire _right.

Exemple

// msl_auto_handle_op_assign.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

ref class ClassA {
protected:
   String^ m_s;
public:
   ClassA(String^ s) : m_s(s) {
      Console::WriteLine( "in ClassA constructor: " + m_s );
   }
   ~ClassA() {
      Console::WriteLine( "in ClassA destructor: " + m_s );
   }

   virtual void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }
};

ref class ClassB : ClassA {
public:
   ClassB( String^ s ) : ClassA( s ) {}
   virtual void PrintHello() new {
      Console::WriteLine( "Hello from {0} B!", m_s );
   }
};

int main()
{
   auto_handle<ClassA> a;
   auto_handle<ClassA> a2(gcnew ClassA( "first" ) );
   a = a2; // assign from same type
   a->PrintHello();

   auto_handle<ClassB> b(gcnew ClassB( "second" ) );
   b->PrintHello();
   a = b; // assign from derived type
   a->PrintHello();

   Console::WriteLine("done");
}

in ClassA constructor: first
Hello from first A!
in ClassA constructor: second
Hello from second B!
in ClassA destructor: first
Hello from second A!
done
in ClassA destructor: second

auto_handle::operator auto_handle

Opérateur de cast de type entre auto_handle les types compatibles.

template<typename _other_type>
operator auto_handle<_other_type>();

Valeur retournée

Cast actuel auto_handle sur auto_handle<_other_type>.

Exemple

// msl_auto_handle_op_auto_handle.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

ref class ClassA {
protected:
   String^ m_s;
public:
   ClassA( String^ s ) : m_s( s ) {}

   virtual void PrintHello() {
      Console::WriteLine( "Hello from {0} A!", m_s );
   }
};

ref class ClassB : ClassA {
public:
   ClassB( String ^ s) : ClassA( s ) {}
   virtual void PrintHello() new {
      Console::WriteLine( "Hello from {0} B!", m_s );
   }
};

int main() {
   auto_handle<ClassB> b = gcnew ClassB("first");
   b->PrintHello();
   auto_handle<ClassA> a = (auto_handle<ClassA>)b;
   a->PrintHello();
}

Hello from first B!
Hello from first A!

auto_handle::operator bool

Opérateur à utiliser auto_handle dans une expression conditionnelle.

operator bool();

Valeur retournée

true si l’objet encapsulé est valide ; false autrement.

Notes

Cet opérateur se convertit en fait en _detail_class::_safe_bool plus sûr que bool parce qu’il ne peut pas être converti en type intégral.

Exemple

// msl_auto_handle_operator_bool.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

int main() {
   auto_handle<String> s1;
   auto_handle<String> s2 = "hi";
   if ( s1 ) Console::WriteLine( "s1 is valid" );
   if ( !s1 ) Console::WriteLine( "s1 is invalid" );
   if ( s2 ) Console::WriteLine( "s2 is valid" );
   if ( !s2 ) Console::WriteLine( "s2 is invalid" );
   s2.reset();
   if ( s2 ) Console::WriteLine( "s2 is now valid" );
   if ( !s2 ) Console::WriteLine( "s2 is now invalid" );
}

s1 is invalid
s2 is valid
s2 is now invalid

auto_handle::operator!

Opérateur à utiliser auto_handle dans une expression conditionnelle.

bool operator!();

Valeur retournée

true si l’objet encapsulé n’est pas valide ; false autrement.

Exemple

// msl_auto_handle_operator_not.cpp
// compile with: /clr
#include <msclr\auto_handle.h>

using namespace System;
using namespace msclr;

int main() {
   auto_handle<String> s1;
   auto_handle<String> s2 = "something";
   if ( s1) Console::WriteLine( "s1 is valid" );
   if ( !s1 ) Console::WriteLine( "s1 is invalid" );
   if ( s2 ) Console::WriteLine( "s2 is valid" );
   if ( !s2 ) Console::WriteLine( "s2 is invalid" );
   s2.reset();
   if ( s2 ) Console::WriteLine( "s2 is now valid" );
   if ( !s2 ) Console::WriteLine( "s2 is now invalid" );
}

s1 is invalid
s2 is valid
s2 is now invalid