write delegate & callback in dll

  • Thread starter Thread starter James Wong
  • Start date Start date
J

James Wong

hi,

I want to write some delegate function to the DLL.
How can I output the value to my main program? (Do not output the value to
the UI)
Any good idea for this program?

Thanks~
For example,

Public Class clsCallBackAdd
Delegate Function _AddDelegate(ByVal intInteger As Integer) As Integer

Private Function _Add(ByVal intInteger As Integer) As Integer
intInteger += 1
Return intInteger
End Function

Public Sub gSetDelegate(ByVal intInteger As Integer)
Dim deleg As _AddDelegate
Dim cb As New AsyncCallback(AddressOf gCallBack)

deleg = AddressOf _Add
deleg.BeginInvoke(intInteger, cb, deleg)
End Sub

Public Sub gCallBack(ByVal ar As IAsyncResult)
......
End Sub
End Class
 
Sorry, James. I didn't quite catch your meaning. What do you mean by output
the value to your main program? Do you mean the return value in the _Add
function? Could you explain a little more detail? Thank you!

Kevin Yu
Microsoft Online Community Support

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I have a windows form (eg. Public Class Form1) will call this DLL,
this form will pass some parameter to the DLL,
When the DLL is processing, my Form1 will do another process.
After the DLL finished the process, how can I get the result value?
 
James said:
I have a windows form (eg. Public Class Form1) will call this DLL,
this form will pass some parameter to the DLL,
When the DLL is processing, my Form1 will do another process.
After the DLL finished the process, how can I get the result value?
Click to expand...

You rise event in dll and catch it on main form.
 
Hi James,

So you mean you need to return the value from _Add function that is
calculated on another thread to the main thread. Am I right?

To return the value, the simplest way is to set the value to a certain
variable in the _Add function instead of returning a value. And in the
callback, make the main thread read from that variable. By the way, when
setting the variable value, we have to use SyncLock statement to lock the
object to make sure that no other thread is writing to it simultanously.

For more information about SyncLock, please check the following link:

http://msdn2.microsoft.com/en-us/library/3a86s51t.aspx

If anything is unclear, please feel free to let me know.

Kevin Yu
Microsoft Online Community Support

==================================================

(This posting is provided "AS IS", with no warranties, and confers no
rights.)
 
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