-- File: Interface_GeneralModule.cdl -- Created: Tue Feb 2 12:20:12 1993 -- Author: Christian CAILLET -- ---Copyright: Matra Datavision 1993 deferred class GeneralModule from Interface inherits TShared ---Purpose : This class defines general services, which must be provided -- for each type of Entity (i.e. of Transient Object processed -- by an Interface) : Shared List, Check, Copy, Delete, Category -- -- To optimise processing (e.g. firstly bind an Entity to a Module -- then calls Module), each recognized Entity Type corresponds -- to a Case Number, determined by the Protocol each class of -- GeneralModule belongs to. uses Transient, HAsciiString from TCollection, InterfaceModel, ShareTool, Check, EntityIterator, CopyTool is FillShared (me; model : InterfaceModel; CN : Integer; ent : Transient; iter : in out EntityIterator) is virtual; ---Purpose : Specific filling of the list of Entities shared by an Entity -- , according a Case Number (formerly computed by -- CaseNum), considered in the context of a Model -- Default calls FillSharedCase (i.e., ignores the model) -- Can be redefined to use the model for working FillSharedCase (me; CN : Integer; ent : Transient; iter : in out EntityIterator) is deferred; ---Purpose : Specific filling of the list of Entities shared by an Entity -- , according a Case Number (formerly computed by -- CaseNum). Can use the internal utility method Share, below Share (me; iter : in out EntityIterator; shared : Transient); ---Purpose : Adds an Entity to a Shared List (uses GetOneItem on ) ListImplied (me; model : InterfaceModel; CN : Integer; ent : Transient; iter : in out EntityIterator) is virtual; ---Purpose : List the Implied References of considered in the context -- of a Model : i.e. the Entities which are Referenced -- while not considered as Shared (not copied if is, -- references not renewed by CopyCase but by ImpliedCase, only -- if referenced Entities have been Copied too) -- FillShared + ListImplied give the complete list of References -- Default calls ListImpliedCase (i.e. ignores the model) -- Can be redefined to use the model for working ListImpliedCase (me; CN : Integer; ent : Transient; iter : in out EntityIterator) is virtual; ---Purpose : List the Implied References of (see above) -- are Referenced while not considered as Shared (not copied if -- is, references not renewed by CopyCase but by -- ImpliedCase, only if referenced Entities have been Copied too) -- FillSharedCase + ListImpliedCase give the complete list of -- Referenced Entities -- The provided default method does nothing (Implied References -- are specific of a little amount of Entity Classes). CheckCase (me; CN : Integer; ent : Transient; shares : ShareTool; ach : in out Check) is deferred; ---Purpose : Specific Checking of an Entity -- Can check context queried through a ShareTool, as required CanCopy (me; CN : Integer; ent : Transient) returns Boolean is virtual; ---Purpose : Specific answer to the question "is Copy properly implemented" -- Remark that it should be in phase with the implementation of -- NewVoid+CopyCase/NewCopyCase -- Default returns always False, can be redefined Dispatch (me; CN : Integer; entfrom : Transient; entto : out mutable Transient; TC : in out CopyTool) returns Boolean is virtual; ---Purpose : Dispatches an entity -- Returns True if it works by copy, False if it just duplicates -- the starting Handle -- -- Dispatching means producing a new entity, image of the -- starting one, in order to be put into a new Model, this Model -- being itself the result of a dispatch from an original Model -- -- According to the cases, dispatch can either -- * just return as equating -- -> the new model designates the starting entity : it is -- lighter, but the dispatched entity being shared might not be -- modified for dispatch -- * copy to -- by calling NewVoid+CopyCase (two steps) or NewCopiedCase (1) -- -> the dispatched entity is a COPY, hence it can be modified -- -- The provided default just duplicates the handle without -- copying, then returns False. Can be redefined NewVoid (me; CN : Integer; entto : out mutable Transient) returns Boolean is deferred; ---Purpose : Creates a new void entity according to a Case Number -- This entity remains to be filled, by reading from a file or -- by copying from another entity of same type (see CopyCase) CopyCase (me; CN : Integer; entfrom : Transient; entto : mutable Transient; TC : in out CopyTool) is deferred; ---Purpose : Specific Copy ("Deep") from to (same type) -- by using a CopyTool which provides its working Map. -- Use method Transferred from CopyTool to work NewCopiedCase (me; CN : Integer; entfrom : Transient; entto : out mutable Transient; TC : in out CopyTool) returns Boolean is virtual; ---Purpose : Specific operator (create+copy) defaulted to do nothing. -- It can be redefined : When it is not possible to work in two -- steps (NewVoid then CopyCase). This can occur when there is -- no default constructor : hence the result must be -- created with an effective definition. -- Remark : if NewCopiedCase is defined, CopyCase has nothing to do -- Returns True if it has produced something, false else RenewImpliedCase (me; CN : Integer; entfrom : Transient; entto : mutable Transient; TC : CopyTool) is virtual; ---Purpose : Specific Copying of Implied References -- A Default is provided which does nothing (must current case !) -- Already copied references (by CopyFrom) must remain unchanged -- Use method Search from CopyTool to work WhenDeleteCase (me; CN : Integer; ent : mutable Transient; dispatched : Boolean) is virtual; ---Purpose : Prepares an entity to be deleted. What does it mean : -- Basically, any class of entity may define its own destructor -- By default, it does nothing but calling destructors on fields -- With the Memory Manager, it is useless to call destructor, -- it is done automatically when the Handle is nullified(cleared) -- BUT this is ineffective in looping structures (whatever these -- are "Implied" references or not). -- -- THUS : if no loop may appear in definitions, a class which -- inherits from TShared is correctly managed by automatic way -- BUT if there can be loops (or simply back pointers), they must -- be broken, for instance by clearing fields of one of the nodes -- The default does nothing, to be redefined if a loop can occur -- (Implied generally requires WhenDelete, but other cases can -- occur) -- -- Warning : tells if the entity to be deleted has been -- produced by Dispatch or not. Hence WhenDelete must be in -- coherence with Dispatch -- Dispatch can either copy or not. -- If it copies the entity, this one should be deleted -- If it doesnt (i.e. duplicates the handle) nothing to do -- -- If is False, normal deletion is to be performed CategoryNumber (me; CN : Integer; ent : Transient; shares : ShareTool) returns Integer is virtual; ---Purpose : Returns a category number which characterizes an entity -- Category Numbers are managed by the class Category -- can be used to evaluate this number in the context -- Default returns 0 which means "unspecified" Name (me; CN : Integer; ent : Transient; shares : ShareTool) returns HAsciiString from TCollection is virtual; ---Purpose : Determines if an entity brings a Name (or widerly, if a Name -- can be attached to it, through the ShareTool -- By default, returns a Null Handle (no name can be produced) -- Can be redefined -- -- Warning : While this string may be edited on the spot, if it is a read -- field, the returned value must be copied before. end GeneralModule;