dal::IsDerivedFrom< D, B > Class Template Reference

#include <isderivedfrom.h>

List of all members.

Classes
class	No
class	Yes
Public Types
enum	{ Is = sizeof(Test(static_cast<D*>(0))) == sizeof(Yes) }

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Detailed Description

template<typename D, typename B>
class dal::IsDerivedFrom< D, B >

The IsDerivedFrom<D,B> class provides class hierarchy information at compile time, allowing the programmer to implement different behaviours for different class hierarchies.

The class provides two constructs. 1: IsDerivedFrom<D,B>::Is == 1 at compile time if D is or derived from B, 0 otherwise. 2: Inheriting from IsDerivedFrom<D,B> will only compile if D is or derived from B.

Example uses: 1: template<typename T, int> class Impl { ... generic implementation ... }; template<typename T, 1> class Impl { ... specialization for B and subclasses ... }; template<typename T> class Class { Impl<T, IsDerivedFrom<T, B>::Is> impl; ... delegating to impl ... };

The above example will provide the generic impl if T is not derived from B (IsDerivedFrom::Is == 0), and the specialization if T is derived from B (IsDerivedFrom::Is == 1).

2: template<typename D> class Class: IsDerivedFrom<D,B> { ... };

The above example will throw a compile error if D is not (derived from) B.

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The documentation for this class was generated from the following file:

• /home/amesfoort/DAL/dal/hdf5/types/isderivedfrom.h