TBoldAbstractSystemHandle¶

Internal.

Declaration¶

TBoldAbstractSystemHandle = class(TBoldElementHandle)

Hierarchy¶

TComponent
TBoldSubscribableComponent
TBoldElementHandle
TBoldAbstractSystemHandle
Direct subclasses
TBoldSystemHandle

Description¶

This is a pure implementation class in order to provide internal separation in Bold. It is of no interest to normal developers. The interesting information is found in TBoldSystemHandle.

Properties¶

Name	Summary	Notes
Active	Use to check or change the status of the SystemHandle
IsDefault	The system is the default system.
System	If TBoldAbstractSystemHandle.Active is true, System is the objectspace owned by the handle.	read-only
SystemTypeInfoHandle	The handle to the system type information to be used by the system

Active¶

property Active: Boolean;

This property decides if the objectspace owned by the handle is to be active or not. When Active is True, the value of the handle is a TBoldSystem as defined by the SystemTypeInfoHandle and PersistenceHandle properties. When Active is false, Value is **nil**. The value is also available correctly typed as System.

Setting Active to true results in the creation of the objectspace, and activation of the persistence mechanism (e.g. database logon).

It is possible to set Active true at design-time. The utility of this varies depending on which features of Bold have been used. Basic types and OCL expressions always work at design time, while anything requiring user-written code such as members derived in code, methods on the domain objects and events on controls (particularly handles and renderers) work only at runtime.

The recommended practice in most cases is to leave Active as false, and to set the AutoActive property instead. but if the applicaiton needs any kind of initialization before the system is activated, then it can be activated manually. The system will be deactivated automatically when the form/datamodule it belongs to is closed/destroyed, but can also be manually shut down by setting this property to false.

Bold Events
Assigning to Active can result in the the following events:

beValueIdentityChanged: Will be sent whenever Active changes value, i.e. the system is created or destroyed.

Note

If the system has any dirty objects when it is shut down it will raise an exception. The correct thing to do is to either save the dirty objects, or discard the system (or ask the user what he prefers).

IsDefault¶

property IsDefault: Boolean;

Set this property to true to specify that the system is the default system. The default system is used in all cases where no explicit system has been given. Note that the concept of default system can be ill-defined at designtime if several Bold projects are open in Delphi:s IDE.

If a application contains several system handles with IsDefault true, one of them will be used as the default system.

In general it is recomended that applications with only one system mark it as the default, while applications with several systems always give an explicit system, and never use a default.

Changing the default system at runtime is definitely not recommended.

System¶

property System: TBoldSystem;

It has the same value as Value, but is correctly typed. If Active is false, the System is **nil**.

Bold events
Since System is a read only property setting it can't directly give rise to events. The following event will however be sent when the system is created or destroyed:

beValueIdentityChanged: Sent when the system is created or destroyed, i.e. when Active changes its value.

SystemTypeInfoHandle¶

property SystemTypeInfoHandle: TBoldSystemTypeInfoHandle;

This property must refer to a TBoldSystemTypeInfoHandle which is in turn connected to the model for the system. Several handles can share the same TBoldSystemTypeInfoHandle, and will in that case be type compatible. This property may not be modified when the system is Active.

Bold events
Since changing SystemTypeInfoHandle will change StaticSystemTypeInfo and StaticBoldType it gives rise to the following events:

beValueIdentityChanged: Will be sent if SystemTypeInfoHandle is assigned a new value.

Methods¶

Name	Summary	Notes
Create	Creates an instance of TBoldAbstractSystemHandle	override
DefaultBoldSystemHandle	The default TBoldSystemHandle if there is one
DefaultBoldSystemTypeInfo	Obsolete
Destroy	Destroys an instance of TBoldAbstractSystemHandle	override
GetActive	Get-method for the Active property	protected, abstract
GetStaticBoldType	Overrides TBoldElementHandle.GetStaticBoldType	protected, override
GetStaticSystemTypeInfo	Overrides TBoldElementHandle.GetStaticSystemTypeInfo	protected, override
GetSystem	Get-method for the System property	protected, abstract
ModelChanged	Bold-internal	protected, abstract
RefersToComponent	Overrides TBoldElementHandle.RefersToComponent	override
SetActive	Set-method for the Active property	protected, abstract

Create¶

constructor Create(owner: TComponent); override;

Create creates an instance of TBoldAbstractSystemHandle.

There is never any need to create an instance of the abstract class TBoldAbstractSystemHandle. TBoldSystemHandle is a more usable subclass.

DefaultBoldSystemHandle¶

class function DefaultBoldSystemHandle: TBoldAbstractSystemHandle;

This class method returns the default TBoldSystemHandle if there is one. This is defined by the property IsDefault.

DefaultBoldSystemTypeInfo¶

class function DefaultBoldSystemTypeInfo: TBoldSystemTypeInfo;

Warning

This property is not used, and will be removed in future releases.

Destroy¶

destructor Destroy; override; See also Ancestor Method

Destroy destroys an instance of TBoldAbstractSystemHandle. Do not call Destroy directly, use Free instead.

GetActive¶

function GetActive: Boolean; virtual; abstract;

Get-method for the Active property

GetStaticBoldType¶

function GetStaticBoldType: TBoldElementTypeInfo; override; See also Ancestor Method

Overrides GetStaticBoldType

GetStaticSystemTypeInfo¶

function GetStaticSystemTypeInfo: TBoldSystemTypeInfo; override; See also Ancestor Method

Overrides GetStaticSystemTypeInfo

GetSystem¶

function GetSystem: TBoldSystem; virtual; abstract;

Get-method for the System property

ModelChanged¶

procedure ModelChanged; virtual; abstract;

Bold-internal

RefersToComponent¶

function RefersToComponent(Component: TBoldSubscribableComponent): Boolean; override; See also Ancestor Method

Overrides RefersToComponent

SetActive¶

procedure SetActive(Value: Boolean); virtual; abstract;

Set-method for the Active property

Generated from the Bold 4.0 help (Help/BfD.chm) by Tools/chm2mkdocs.py; member lists reflect Bold 4.0, see the source for members added since.