I understand that .NET is multi-threaded and that is a good thing, but I continually run into issues when I have a background worker for example that is updating some control on my form and I have to do:
Private Sub SetRowCellBoolValueThreadSafe(ByVal row As Integer, ByVal col As Integer, ByVal value As Boolean)
If dgvDatabase.InvokeRequired Then
Dim d As New SetRowCellBoolValueCallback(AddressOf SetRowCellBoolValue)
Me.Invoke(d, New Object() {row, col, value})
Else
SetRowCellBoolValue(row, col, value)
End If
End Sub
Delegate Sub SetRowCellBoolValueCallback(ByVal row As Integer, ByVal col As Integer, ByVal value As Boolean)
Private Sub SetRowCellBoolValue(B开发者_如何学GoyVal row As Integer, ByVal col As Integer, ByVal value As Boolean)
dgvDatabase.Rows(row).Cells(col).Value = value
End Sub
My question is why is this not built into the framework - surely if I am trying to update a DataGridView
it should be intelligent enough to know when the update is from another thread and it could do all the above itself?
The would mean turning every operation on a UI control into a delegate, just in case it needed to be marshalled to a different thread. That would be hugely expensive. Additionally, it presupposes that you always want to do the same thing - use Invoke
rather than BeginInvoke
for example.
I agree it's a bit of a pain in the neck to have to do this manually, but the next versions of C# and VB should make life a lot easier with async methods.
(As an aside, I don't think you really want to use ByRef
for all those parameters... is it possible that you're not really clear what ByRef
means?)
I don't work for Microsoft but I would guess,
Most GUI code written with .NET is not Multi-threaded so, why incur the burden of checking for the minority case. The developer should know it there is a potential for multi-threading and check when appropriate.
In the specific case of a BackgroundWorker, I would suggest you use its progress reporting feature.
Your BackgroundWorker calls ReportProgress
, optionally passing an object with some state information. This raises the ProgressChanged
event on the UI thread, which can update controls on your form, using the state information passed from the background worker.
Progress reporting is not limited to updating a ProgressBar or similar.
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