How can I create a new thread AddressOf a function with parameters in VB?

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萌比男神i
萌比男神i 2020-12-21 00:28

When option strict is OFF, works fine. ON, I get overload resolution failure:

Dim _thread1 As Thread

Private Sub test2(boolTest As Boolean)
    \' Do someth         


        
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3条回答
  • 2020-12-21 01:08

    You should follow al-eax's answer, but another way would be to not pass parameters in the Thread.Start() function at all, but rather evaluate it in the test sub...

    Dim _thread1 As Thread
    
    Private Sub test()
        If someTest = True then    
            _thread1 = New Thread(AddressOf test2)
            _thread1.Start()
        End If
    End Sub
    
    Private Sub test2()
        /.../
    End Sub
    

    ...or declare it as a global variable...

    Dim _thread1 As Thread
    Dim boolTest As Boolean
    
    Private Sub test()
        boolTest = True
    
        _thread1 = New Thread(AddressOf test2)
        _thread1.Start()
    End Sub
    
    Private Sub test2()
        If boolTest = True Then
            /.../
        End If
    End Sub
    
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  • 2020-12-21 01:11

    When you start a thread this way your function must have one or less parameters. If you specify one parameter, it must be from type Object.

    In your function you can simply cast this object parameter to your datatype:

    private sub startMe(byval param as Object)
         dim b as Boolean = CType(param, Boolean)
         ...
    end sub
    

    When you want to pass multiple parameters, you can put them together into a class like this:

    public class Parameters
         dim paramSTR as String
         dim paramINT as Integer
    end class
    
    private sub startMe(byval param as Object)
         dim p as Parameters = CType(param, Parameters)
         p.paramSTR = "foo"
         p.paramINT = 0
         ...
    end sub
    

    To start your Thread:

    dim t as new Thread(AddressOf startMe)
    dim p as new Parameters
    p.paramSTR = "bar"
    p.oaramINT = 1337
    t.start(p)
    
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  • 2020-12-21 01:22

    It looks like it's because the method you're delegating to has a Boolean parameter: '...does not allow narrowing...' Change the signature to use Object.

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