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



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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)

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