TPersistent

[Properties (by Name)][Methods (by Name)][Events (by Name)]

Base class for streaming system and persistent properties.

Declaration

Source position: classesh.inc line 430

Type
  TPersistent = class (TObject, IFPObserved)
  private
    FObservers : TFPList;
    procedure AssignError(Source: TPersistent);
  protected
    procedure AssignTo(Dest: TPersistent);  Virtual;
    procedure DefineProperties(Filer: TFiler);  Virtual;
    function GetOwner : TPersistent;  Dynamic;
  public
    destructor Destroy;  Override;
    procedure Assign(Source: TPersistent);  Virtual;
    procedure FPOAttachObserver(AObserver: TObject);
    procedure FPODetachObserver(AObserver: TObject);
    procedure FPONotifyObservers(ASender: TObject; 
                                AOperation: TFPObservedOperation; 
                                Data: Pointer);
    function GetNamePath : string;  Virtual;
  end
  ;

Description

TPersistent is the basic class for the streaming system. Since it is compiled in the {$M+} state, the compiler generates RTTI (Run-Time Type Information) for it and all classes that descend from it. This information can be used to stream all properties of classes.

It also introduces functionality to assign the contents of 2 classes to each other.

TPersistent implements the IFPObserved interface for the benefit of descendant classes, but does not call IFPObserved.FPONotifyObservers . Descendants such as TStrings and TCollection and TCollectionItem do use it.

Members

Member	Type	Visibility	Description
Assign	Method	public	Assign the contents of one class to another.
AssignError	Method	private	Raises an EConvertError when an error occurs during assignment.
AssignTo	Method	protected	Generic assignment function.
DefineProperties	Method	protected	Declare non-published properties that need to be streamed.
Destroy	Method	public	Destroys the TPersistent instance.
FObservers	Field	private
FPOAttachObserver	Method	public	Add an observer to the list of observers.
FPODetachObserver	Method	public	Remove an observer from the list of observers
FPONotifyObservers	Method	public	Notify observers of changes.
GetNamePath	Method	public	Returns a string that can be used to identify the class instance.
GetOwner	Method	protected	Returns the owner of the component.

Inheritance

Class	Description
TPersistent(IFPObserved)	Base class for streaming system and persistent properties.

See also

Name	Description
IFPObserved	Interface implemented by an object that can be observed.
TCollection	Base class to manage collections of named objects.
TCollectionItem	Basic object that is managed by a TCollection class.
TComponent	Base class for all components that need owner-owned functionality.
TFPList	Class to manage collections of pointers.
TStrings	Class to manage arrays or collections of strings