IlsInvertedRelation

Category

Modeling class template

Inheritance Path

IlsInvertedRelation

Related Pattern

Bridge

Description

Rogue Wave® Server lets you invert a relation by maintaining a back pointer to the origin of that relation. This pointer is declared as an instance of the class template IlsInvertedRelation and maintained by means of the functions setContext and unsetContext. A relation of type IlsInvertedRelation contains an entry. Modifying it may therefore trigger the recomputation of derived members or notification.

TargetType and OriginType must directly or transitively derive from IlsEntity or IlsObject.

The IlsInvertedRelation template makes a forward declaration of the function IlsViewed* Ils2Viewed(OriginType*) and uses it in its implementation. This to avoid the compiler to require visibility on the class OriginType when instantiating the inverted relation template. The implementation of the Ils2Viewed function is expanded by the macro ILS_OBJECT_DECL or its derivatives. If you do not want to use that macro because the type OriginType is not notified by views, you can define your own function in a source of your application that has visibility on the class OriginType, as follows:

Ils2Viewed* Ils2Viewed(TargetType* obj){return obj;}

Library

Header File

#include <ilserver/model.h>

Synopsis

template <class TargetType, class OriginType>

class IlsInvertedRelation

{

public:

IlsInvertedRelation

(TargetType&,

IlsActivity activity=IlsModel::getDefaultActivity());

Accessors

TargetType& getTarget();

OriginType* getValue();

Modifiers

Myself& set(OriginType* rhs);

Myself& clear();

Notification

IlsBoolean isModified();

OriginType* getOldvalue();

Operators

operator OriginType*();

OriginTypeP operator->();

OriginType& operator*();

IlsBoolean operator!();

IlsBoolean operator==(OriginType* rhs);

IlsBoolean operator!=(OriginType* rhs);

IlsBoolean operator==(Myself& rhs);

IlsBoolean operator!=(Myself& rhs);

Myself& operator=(OriginType* rhs);

Myself& operator=

(IlsInvertedRelation<TargetType,OriginType>& rhs);

};

Constructor

IlsInvertedRelation

(TargetType&,

IlsActivity activity=IlsModel::GetDefaultActivity());

As its first argument, this constructor takes a reference to the type in which the relation is declared. It initializes the back pointer to zero. The argument activity specifies whether the relation is active or not. A relation is active if its modification sets off the recomputation of derived data members. The default value is the one returned by the static member function IlsModel::GetDefaultActivity, which is ILS_INACTIVE by default.

Member Functions

Accessors

TargetType& getTarget();

This member function returns the target of the relation.

OriginType* getValue();

This member function returns a pointer to the origin of the relation. It is useful especially when the conversion operator cannot be used or when the compiler is likely to encounter multiple user-defined conversions.

Modifiers

Myself& set(OriginType* rhs);

This member function assigns a new origin to the inverted relation.

Myself& clear();

This member function sets the relation to zero.

Notification

IlsBoolean isModified();

During a notification phase, this member function returns IlsTrue only if the relation has been modified since the last notification phase.

OriginType* getOldvalue();

During a notification phase, this member function returns a smart pointer to the object that was the target of the relation before the notification phase.

Operators

These operators let you use inverted relations as if they were pointers.

operator OriginType*();

This operator converts the relation to a pointer to an object of the OriginType.
It is equivalent to the member function getValue (see above).

OriginTypeP operator->();

This dereference operator returns the origin of the relation.

OriginType& operator*();

This indirection operator returns a reference to the origin of the relation.

IlsBoolean operator!();

This operator returns IlsTrue if the inverted relation is set to 0.

IlsBoolean operator==(OriginType* rhs);

This operator checks whether the origin-type is equal to another origin-type.

IlsBoolean operator!=(OriginType* rhs);

This operator checks whether the origin-type is not equal to another origin-type.

IlsBoolean operator==(Myself& rhs);

This operator checks whether the inverted relation is equal to another inverted relation.

IlsBoolean operator!=(Myself& rhs);

This operator checks whether the inverted relation is not equal to another inverted relation.

Myself& operator=(OriginType* rhs);

This operator assign a new origin to the inverted relation.

Myself& operator=(IlsInvertedRelation<TargetType,OriginType>& rhs);

This operator assigns an inverted relation to the inverted relation.