Question

I have a property getter with a lock like this one:

Public ReadOnly Property ActiveClientList() as List(Of TcpClient)
    Get
        SyncLock(m_activeClientListLock)
            Return m_activeClientList
        End SyncLock
    End Get
End Property

When I do a ForEach loop when is the property getted? I mean, in this loop when the list is locked? At the first check? On each iteration? At the whole loop?

For Each client as TcpClient in Me.ActiveClientList

Next

Thanks in advance!

Answer 1

For Each is actually syntactic sugar. The compiler expands it to this:

Dim enumerator As IEnumerator(Of TcpClient)

enumerator = Me.ActiveClientList.GetEnumerator()

While enumerator.GetNext()

    Dim client As TcpClient
    client = enumerator.Current

    'Loop body inserted here.'

End While

Apologies if this isn’t true VB.NET (I’m a C# boy).

As you can see, the call to ActiveClientList happens once, right at the start of the loop.