OPC Studio User's Guide and Reference
EasyDAItemSubscriptionArguments Constructor(DAItemGroupArguments,EasyDAItemChangedEventHandler)



OpcLabs.EasyOpcClassicCore Assembly > OpcLabs.EasyOpc.DataAccess.OperationModel Namespace > EasyDAItemSubscriptionArguments Class > EasyDAItemSubscriptionArguments Constructor : EasyDAItemSubscriptionArguments Constructor(DAItemGroupArguments,EasyDAItemChangedEventHandler)
The item group arguments object to be copied from.

The value of this parameter cannot be null (Nothing in Visual Basic).

A callback method to be invoked for each significant item change.

The value of this parameter can be null (Nothing in Visual Basic).

Initializes a new EasyDAItemSubscriptionArguments object from DAItemGroupArguments, and with specified callback method.
Syntax
'Declaration
 
Public Function New( _
   ByVal args As DAItemGroupArguments, _
   ByVal callback As EasyDAItemChangedEventHandler _
)
'Usage
 
Dim args As DAItemGroupArguments
Dim callback As EasyDAItemChangedEventHandler
 
Dim instance As New EasyDAItemSubscriptionArguments(args, callback)
public EasyDAItemSubscriptionArguments( 
   DAItemGroupArguments args,
   EasyDAItemChangedEventHandler callback
)
public:
EasyDAItemSubscriptionArguments( 
   DAItemGroupArguments^ args,
   EasyDAItemChangedEventHandler^ callback
)

Parameters

args
The item group arguments object to be copied from.

The value of this parameter cannot be null (Nothing in Visual Basic).

callback
A callback method to be invoked for each significant item change.

The value of this parameter can be null (Nothing in Visual Basic).

Exceptions
ExceptionDescription

A null reference (Nothing in Visual Basic) is passed to a method that does not accept it as a valid argument.

This is a usage error, i.e. it will never occur (the exception will not be thrown) in a correctly written program. Your code should not catch this exception.

Remarks
If callback is a null reference, only the notification events are generated, but no callback method is invoked.
Requirements

Target Platforms: .NET Framework: Windows 10 (selected versions), Windows 11 (selected versions), Windows Server 2016, Windows Server 2022; .NET: Linux, macOS, Microsoft Windows

See Also