TBoldMember¶

The members of Bold objects are of the type TBoldMember.

Declaration¶

TBoldMember = class(TBoldDomainElement)

Hierarchy¶

TObject
TBoldMemoryManagedObject
TBoldFlaggedObject
TBoldSubscribableObject
TBoldElement
TBoldDomainElement
TBoldMember
Direct subclasses
TBoldAttribute
TBoldList
TBoldObjectReference

Description¶

The members of Bold objects are of the type TBoldMember. But a TBoldMember doesn't have to belong to a Bold object. It can be, and is often, used as a standalone variable or constant. In that case, its BoldMemberRtInfo and OwningObject properties are **nil**.

Properties¶

Name	Summary	Notes
AsIBoldValue	The IBoldValue interface.	read-only
BoldMemberRTInfo	The model information for the member	read-only
BoldPersistenceState	The relationship between the member's value in memory and in the persistent storage.
BoldSystem	The BoldSystem that the member belongs to.	read-only
Derived	Indicates if the member is derived.	read-only
Deriver	There is normally no need for the programmer to access the deriver directly.	read-only
IsPartOfSystem	Indicates if the member is part of a BoldSystem.	read-only
OldValue	Bold-internal	read-only
OwningObject	The Bold object the member is a member of.	read-only
Touched	Bold-internal	read-only

AsIBoldValue¶

property AsIBoldValue[Mode:TBoldDomainElementProxyMode]: IBoldValue;

Use this property to get the IBoldValue for the member. This is used internally.

BoldMemberRTInfo¶

property BoldMemberRTInfo: TBoldMemberRTInfo;

If the TBoldMember is a member of a Bold object, the BoldMemberRTInfo property will be assigned. It contains the model information for the member.

BoldPersistenceState¶

property BoldPersistenceState: TBoldValuePersistenceState;

The persistence state of a Bold member reflects the relationship between its value in memory and in the persistent storage. It tells us which of the two is the most recent.

If the state of a member is bvpsInvalid it means that the value in memory is not correct. It will be fetched automatically when the member is accessed. After the value has been fetched the state will become bvpsCurrent, meaning that the value in memory is the same as the value in the persistent storage. If the value of the member is changed in memory the state will change to bvpsModified, implying that the new value should be written to the persistent storage. Finally, the bvpsTransient state tells us that the member only exists in memory, either because the object it belongs to is transient, or because the member is marked as transient in the model.

Calling Invalidate makes a member 'forget' that it has been fetched. This changes its state from bvpsCurrent to bvpsInvalid. It is not allowed to invalidate members in bvpsModified state. Similarly, Discard makes a member 'forget' that it has been modified. It changes it from bvpsModified to bvpsInvalid.

Finally, members can change state from bvpsTransient to bvpsModified. This happens automatically if the object the member belongs to becomes persistent. See TBoldObject.BoldMakePersistent.

Before a member's value is modified in memory the method CanModify is called to see if modifying the member is allowed. CanModify, among other things, checks the virtual MayModify method and the bqMayModify query-event. If the modification is allowed the virtual PrepareModify method is called and the event bePrepareModify is sent. After the value has been changed the virtual method CompleteModify is called and the event beCompleteModify is sent.

BoldSystem¶

property BoldSystem: TBoldSystem;

For a member that is part of a Bold object, this is the system that the object belongs to. For standalone members, it is **nil**.

Derived¶

property Derived: Boolean;

Indicates if the member is derived.

Deriver¶

property Deriver: TBoldEventPluggedDeriver;

There is normally no need for the programmer to access the deriver directly.

IsPartOfSystem¶

property IsPartOfSystem: Boolean;

If IsPartOfSystem is true, the BoldSystem property is valid. If not, accessing BoldSystem will raise an exception.

OldValue¶

property OldValue: IBoldValue;

Bold-internal.

OwningObject¶

property OwningObject: TBoldObject;

Returns the Bold object the member is a member of. If the member is not member of a Bold object, the function returns **nil**.

Touched¶

property Touched: Boolean;

Bold-internal

Methods¶

Name	Summary	Notes
AtTime		virtual
CanModify	If the member is allowed to be modified
CanRead	Indicates if the value of the member may be read
CanUpdate	If the member is allowed to be updated
Changed	Called internally when the value of the member has changed.	protected
Clone	Makes a copy of the member.
CloneIfPossible	This will create a clone of the member and copy the contents.	protected, override
CompleteModify	Occurs directly after the member is modified.	protected, virtual
CompleteUpdate	Virtual method that is called after a member has been updated in the persistent storage	protected, virtual
Create	Creates an element that is not part of a Bold object.
CreateWithTypeInfo	Constructor with Bold type information
Destroy	Destructor	override
Discard	Discards changes in memory
DoStartModify	Bold-internal method that performs preparations needed before modifying the value of a member.	protected
EndModify	Called by member subclasses after the value has been modified.	protected
EnsureContentsCurrent	If the value of the member is not current, make it current.
FailModify	Called by member subclasses if a modification fails.	protected
FreeContent	Releases the memory used for the data value.	protected, virtual
GetAsList	Overrides TBoldElement.GetAsList	override
GetAsValue	Bold-internal	override
GetBoldDirty	Overrides TBoldDomainElement.GetBoldDirty	protected, override
GetBoldPersistenceState	Get-method for the BoldPersistenceState property	protected
GetBoldType	Overrides TBoldElement.GetBoldType	protected, override
GetDisplayName	Overrides TBoldElement.GetDisplayName	protected, override
GetEvaluator	Overrides TBoldElement.GetEvaluator	protected, override
GetStreamName	Name that identifies the type of the object for the streaming mechanisms.	protected, virtual
InitializeMember	Bold-internal	protected, virtual
Invalidate
IsEqualToValue	Similar to IsEqual, but compares with a IBoldValue.	virtual
MayModify	Override this function and return false to prohibit the modify state transition.	protected, virtual
MayUpdate	Override this function and return false to prohibit the update state transition.	protected, virtual
MemberHasSubscribers	True if there is anything subscribing to the member.
ObserverMayModify		override
PreChange	Called by subclasses before the data value changes.	protected
PrepareModify	Override this method to add behaviour before a member is modified.	protected, virtual
PrepareUpdate	Override this method to add behaviour before a member is saved to persistent storage.	protected, virtual
ProxyClass	The Delphi class used by ProxyInterface	protected, abstract
ProxyInterface	Overrides TBoldElement.ProxyInterface	override
Refetch	Fetches the value from persistent storage.
RetrieveProxyInterface	Internal. Called by subclasses.	protected
SetBoldPersistenceState	Bold-internal. Sets the persistence state.	protected
StartModify		protected, virtual
StateError	Overrides TBoldDomainElement.StateError	protected, override
StoreInUndo	Bold-internal

AtTime¶

function AtTime(Time: TBoldTimestampType): TBoldMember; virtual;

Returns the member as it looked at the time point identified by the Time time stamp.

Note

This feature is only available in the Object Versioning Extension to Bold for Delphi.

CanModify¶

function CanModify: Boolean;

Returns True if the member is allowed to be modified. A programmer can disallow modify either by overriding the virtual MayModify function or subscribing to the bqMayModify query.

CanRead¶

function CanRead(Subscriber: TBoldSubscriber): Boolean;

Returns True if the value of the member may be read. A programmer can disallow reading a member by subscribing to the bqMayRead query. If a Subscriber is passed to the function, subscriptions will be placed to notify when the result of MayRead may have changed.

CanUpdate¶

function CanUpdate: Boolean;

Returns True if the member is allowed to be updated. A programmer can disallow update either by overriding the virtual MayUpdate function or subscribing to the bqMayUpdate query.

Changed¶

procedure Changed(Event: TBoldEvent; const Args: array of const);

This method shall be called whenever the contents (technical value) of the member has changed. The Event and Args parameters should contain the values corresponding to a call to SendExtendedEvent. The event will be sent unless BoldPersistenceState is bvpsInvalid.

It is important that all subclasses to TBoldMember, i.e. custom attributes call this method.

Clone¶

function Clone: TBoldMember;

Makes a copy of the member. The resulting member will be of the same type and will contain the same value as the original.

CloneIfPossible¶

function CloneIfPossible: TBoldElement; override; See also Ancestor Method

This will create a clone of the member and copy the contents.

CompleteModify¶

procedure CompleteModify; virtual;

Override this method to add behaviour after a member is modified. The default implementation is empty.

See Also

TBoldValuePersistenceState

CompleteUpdate¶

procedure CompleteUpdate; virtual;

Override this method to add behaviour after a member is updated in the persistent storage. The default implementation is empty.

Create¶

constructor Create;

Contructor for member. Will create a member that is freestanding from any Bold object or system.

CreateWithTypeInfo¶

constructor CreateWithTypeInfo(ElementTypeInfo: TBoldElementTypeInfo);

As TBoldMember is an abstract class, CreateWithTypeInfo should not be called directly on TBoldMember, but on one of its concrete subclasses. Use this constructor instead of Create to explicitly specify the type info for the member. This is useful for creating members with types that are not in the default BoldSystem.

Destroy¶

destructor Destroy; override; See also Ancestor Method

Destructor

Discard¶

procedure Discard;

If any changes have been made to the member since it was fetched from persistent storage, or updated to persistent storage, these changes will be lost. This means that a member with BoldPersistenceState = bvpsModified will have its persistence state changed to bvpsInvalid.

DoStartModify¶

procedure DoStartModify;

Bold-internal method that performs preparations needed before modifying the value of a member.

EndModify¶

procedure EndModify;

Triggers the EndModify state transition. EndModify will be called automatically when a member is modified.

See Also

TBoldValuePersistenceState

EnsureContentsCurrent¶

procedure EnsureContentsCurrent;

If the value of the member is not current, make it current. A persistent member will be fetched, and a derived attribute will be derived.

FailModify¶

procedure FailModify;

Triggers the FailModify state transition. FailModify will be called automatically when a modify operation fails.

See Also

TBoldValuePersistenceState

FreeContent¶

procedure FreeContent; virtual;

This method is implemented by memory consuming subclasses, such as blob attributes and multilinks, to release memory. It will be called when the value is not needed any more.

GetAsList¶

procedure GetAsList(ResultList: TBoldIndirectElement); override; See also Ancestor Method

Sets ResultList to point to a TBoldMemberList containing the member.

GetAsValue¶

procedure GetAsValue(ResultElement: TBoldIndirectElement); override; See also Ancestor Method

Bold-internal. Overrides GetAsValue.

GetBoldDirty¶

function GetBoldDirty: Boolean; override; See also Ancestor Method

Overrides GetBoldDirty. A member is dirty if its persistence state is bvpsModified; if its value has been modified in memory.

GetBoldPersistenceState¶

function GetBoldPersistenceState: TBoldValuePersistenceState;

Get-method for the BoldPersistenceState property

GetBoldType¶

function GetBoldType: TBoldElementTypeInfo; override; See also Ancestor Method

Overrides TBoldElement.GetBoldType

GetDisplayName¶

function GetDisplayName: String; override; See also Ancestor Method

Overrides GetDisplayName. The display name for a member that is part of a Bold object is ".".

GetEvaluator¶

function GetEvaluator: TBoldEvaluator; override; See also Ancestor Method

Overrides GetEvaluator. If the member belongs to a system, that system's evaluator is used.

GetStreamName¶

function GetStreamName: string; virtual;

Name that identifies the type of the object for the streaming mechanisms.

InitializeMember¶

procedure InitializeMember(AOwningElement: TBoldDomainElement; ElementTypeInfo: TBoldElementTypeInfo); virtual;

Bold-internal

Invalidate¶

procedure Invalidate;

Call this method if you beleive that the value of the member may have changed in the persistent storage. This will cause the member to be refetched the next time its value is accessed. Members with BoldValuePersistenceState = bvpsCurrent will have their persistence state changed to bvpsInvalid. Calling Invalidate on modified or transient members will cause an exception to be raised.

IsEqualToValue¶

function IsEqualToValue(Value: IBoldValue): Boolean; virtual;

Similar to IsEqual, but compares with an IBoldValue.

MayModify¶

function MayModify: Boolean; virtual;

Override this function and return false to prohibit the modify state transition. See also CanModify and StartModify.

MayUpdate¶

function MayUpdate: Boolean; virtual;

Override this function and return false to prohibit the update state transition. See also CanUpdate.

MemberHasSubscribers¶

function MemberHasSubscribers: Boolean;

True if there is anything subscribing to the member. See Subscription.

ObserverMayModify¶

function ObserverMayModify(Observer: TObject): Boolean; override; See also Ancestor Method

Overrides ObserverMayModify

PreChange¶

procedure PreChange;

Called by subclasses before the data value changes.

PrepareModify¶

procedure PrepareModify; virtual;

Override this method to add behaviour before a member is modified. The default implementation is empty.

See Also

TBoldValuePersistenceState

PrepareUpdate¶

procedure PrepareUpdate; virtual;

Override this method to add behaviour before a member is saved to persistent storage. The default implementation is empty.

See Also

TBoldValuePersistenceState

ProxyClass¶

function ProxyClass: TBoldMember_ProxyClass; virtual; abstract;

The Delphi class used by ProxyInterface. Implemented by subclasses.

ProxyInterface¶

function ProxyInterface(const IId: TGUID; Mode: TBoldDomainElementProxyMode; out Obj): Boolean; override; See also Ancestor Method

Overrides ProxyInterface.

Refetch¶

procedure Refetch;

Fetches the value from persistent storage regardless of whether the member is already fetched. This does not discard the value of a modified member. Modified members are not affected by a call to Refetch.

RetrieveProxyInterface¶

function RetrieveProxyInterface(const IId: TGUID; Mode: TBoldDomainElementProxyMode; out Obj; const InterfaceName: string): Boolean;

Internal. This method is called by subclasses to implement ProxyInterfaces.

SetBoldPersistenceState¶

procedure SetBoldPersistenceState(Value: TBoldValuePersistenceState);

Bold-internal. Sets the persistence state. Normally there is no need to call this method.

StartModify¶

function StartModify: Boolean; virtual;

Triggers the StartModify state transition. StartModify will be called automatically before a member is updated. The result will be True if the state transition was succesful. CanModify will return the same value as StartModify without performing the state transition.

See Also

TBoldValuePersistenceState

StateError¶

procedure StateError(S: String); override; See also Ancestor Method

Overrides TBoldDomainElement

StoreInUndo¶

function StoreInUndo: Boolean;

Bold-internal. Used by the undo-mechanism.

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.