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-- File: Standard_Persistent.cdl
-- Created: Mon Aug 24 13:11:56 1992
-- Author: Ramin BARRETO
-- <rba@sdsun3>
deferred class Persistent from Standard
inherits
Storable from Standard
---Purpose:
-- The root of the entire persistent class hierarchy.
--
-- Persistence is the ability to create objects which
-- outlive the application process.
-- Objects stored in the database must be instances
-- of a Persistent-derived class.
-- The collection of persistent classes used by an
-- application constitute its application data schema.
--
-- Open CASCADE provides persistent classes to describe:
-- - ASCII (normal 8 bit character type) and
-- Unicode (16 bit character type) strings,
-- - arrays of persistent data,
-- - geometric data structures,
-- - topological data structures.
--
-- The user can enrich this set of persistent classes by describing
-- his own persistent data structures inheriting from Persistent
-- for use in a store and retrieve programming context.
--
-- Warning:
--
-- Persistent objects are manipulated in programs by handles.
-- A handle to a persistent object behaves like
-- a pointer to the entire database address space.
-- In using such a handle, you transparently operate on the object
-- in the database, providing that you do this inside a transaction.
--
-- However "Persistent Programming" (i.e. the programming
-- technique whereby the application operates on persistent
-- objects, that is, directly in the database, within a transaction)
-- is not supported by Open CASCADE.
uses
Type from Standard
,Boolean from Standard
,OId from Standard
is
ShallowCopy (me) returns mutable like me is deferred;
---Purpose: Returns a copy at the first level of <me>.
-- The objects referenced are not copied.
-- Entities copied by ShallowCopy are equal.
---C++: function call
---Level: Advanced
Delete (me: mutable) is redefined;
---Purpose: Deletes this object.
DynamicType (me) returns Type is virtual;
---Purpose:
-- Returns the type object representing the actual type of the object.
-- There is one type object per Persistent-derived class.
--
-- Example:
--
-- Handle(Standard_Persistent) p;
-- Handle(Standard_Type) t;
-- p = new PGeom_CartesianPoint(0.,0.,0.);
-- t = STANDARD_TYPE(PGeom_CartesianPoint);
-- assert(p->DynamicType() == t);
IsInstance (me; TheType : Type) returns Boolean is static;
---Purpose:
-- Returns true if the actual type of the object is equal to the given type.
--
-- Example:
--
-- Handle(Standard_Persistent) p;
-- Handle(Standard_Type) t;
-- p = new PGeom_CartesianPoint(0.,0.,0.);
-- t = STANDARD_TYPE(PGeom_CartesianPoint);
-- assert(p->IsInstance(t));
--
-- Warning:
--
-- For most purposes it is better to use IsKind because IsInstance
-- rejects objects being subtype of the given type.
IsKind (me; TheType : Type) returns Boolean
---Purpose:
-- Returns true if <me> is an instance of <aType> or an
-- instance of any class that inherits from <aType>.
-- All persistent objects are a kind of Object class.
--
-- Example:
--
-- Handle(Standard_Persistent) p;
-- Handle(Standard_Type) tp, tt;
-- p = new PGeom_CartesianPoint(0.,0.,0.);
-- tp = STANDARD_TYPE(PGeom_CartesianPoint);
-- tt = STANDARD_TYPE(Standard_Persistent);
-- assert(p->IsKind(tp));
-- assert(p->IsKind(tt));
is static;
This (me) returns mutable Persistent
---Purpose: Returns a handle on the object.
-- This method is useful only in constructors of persistent
-- objects when you need a handle on the object being constructed.
-- It guarantees that, whatever the underlying database
-- you are using, the object will not be swapped out
-- during its construction.
is static protected;
end Persistent from Standard;
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