Extremely simple demo of multithreading in twinBASIC
Normally, when you call MsgBox, code execution stops until you respond to it. In this demo, you'll see the following line continues and updates the label, before we decide to manually wait for it.
(Feb 24th 2023: Updated to use a TextBox instead of a label due to a rendering issue with lightweight controls not updating immediately; UI improvements)
(Nov 9th 2022: Updated for x64/bugfixes)
This is just a simple proof-of-concept showing you can safely multithread in twinBASIC via API without relying on the elaborate hacks VB6 requires to call CreateThread:
Private Declare PtrSafe Function GetCurrentThreadId Lib "kernel32" () As Long
Private Declare PtrSafe Function CreateThread Lib "kernel32" ( _
ByRef lpThreadAttributes As Any, _
ByVal dwStackSize As Long, _
ByVal lpStartAddress As LongPtr, _
ByRef lpParameter As Any, _
ByVal dwCreationFlags As Long, _
ByRef lpThreadId As Long) As LongPtr
Private Declare PtrSafe Function WaitForSingleObject Lib "kernel32" ( _
ByVal hHandle As LongPtr, _
ByVal dwMilliseconds As Long) As Long
Private Const INFINITE = -1&
Private Sub Command1_Click() Handles Command1.Click
Dim lTID As Long
Dim lCurTID As Long
Dim hThreadNew As LongPtr
lCurTID = GetCurrentThreadId()
hThreadNew = CreateThread(ByVal 0, 0, AddressOf TestThread, ByVal 0, 0, lTID)
Text1.Text = "Thread " & lCurTID & " is waiting on thread " & lTID
Dim hr As Long
hr = WaitForSingleObject(hThreadNew, 30000&) 'Wait 30s as a default. You can use INFINITE instead if you never want to time out.
Text1.Text = "Wait end code " & CStr(hr)
End Sub
Public Sub TestThread()
MsgBox "Hello thread"
End Sub