DllCallBackRegister + DllCallBackGetPtr = AddressOf in Vb.net ?

[kcvinu]

Hi all,

I am reading subclassing and hooking in vb.net. When i read the lesson about subclass a window, this thought came to my mind. So i am asking this for a clarification.

Using DllCallBackRegister + DllCallBackGetPtr is equal to use AddressOf in Vb.net ? If so i think, i need to make a new function to club the both autoit functions in order to make something equal to AddressOf.

[TheSaint]

This is not Developer Chat, this is General Chat, where we don't discuss the intricacies of programming.

I suggest you report your topic and ask a MOD to move it to Developer General Discussion.

[kcvinu]

@TheSaint Oh, i am so sorry TheSaint. By report, you mean i am commenting a mod's name here and tell the matter ?. 

[BrewManNH]

No, he means click the Report Post link

[TheSaint]

No worries.

At the top of each post, it says Report Post.

[minxomat]

1 hour ago, kcvinu said:

Using DllCallBackRegister + DllCallBackGetPtr is equal to use AddressOf in Vb.net ? If so i think, i need to make a new function to club the both autoit functions in order to make something equal to AddressOf.

Uhm, could you rephrase that? This is a very weird sentence.

A few hints though:

AddressOf

This .NET operator creates a delegate. One example of this is to provide other methods with handlers to digest events (eg. clicking a button).

Pointers

DllCallbackGetPtr get's a real pointer to an AutoIt callback method. Native code (not .NET) can use this pointer to call functions in your AutoIt script. This is not at all comparable to AddressOf, since the Dllxxx function use actual pointers. The last version of VB to support real pointers (and pointer arithmetic) is VB6. VB14's AddressOf has nothing to do with this. What you are looking for is

Function References

This (relatively) new feature in AutoIt allows you to pass references to functions as values in AutoIt. This can be used for the same purpose as AddressOf, here's an example:

; Actual code
ProvokeError()                ; will do nothing
ProvokeError(True)            ; will show error in console
ProvokeError(True, UIHandler) ; will show error MessageBox


; Examples of handlers for different purposes
Func ConsoleHandler($msg)
    ConsoleWrite("!> Error. Message: " & $msg & @LF)
EndFunc

Func UIHandler($msg)
    If MsgBox(4, "Error", "Message: " & $msg & @CRLF & "Do you want to exit?") = 6 Then Exit
EndFunc

; This will do something
Func ProvokeError($bFail = False, $hErrorHandler = ConsoleHandler)
    If $bFail Then $hErrorHandler("$bFail was true.")
EndFunc

 

Edited February 16, 2016 by minxomat

[kcvinu]

@minxomat , 

I think i need to read more about AddressOf. Any how, the book i read was related to vb6. So i think the AdderssOf in vb.net and AddressOf in vb6 are equal. The book says that in vb6 they used AddressOf as a function pointer. Then i have searched this forum and got some good examples of DllCallBackRegister function. And in your example, i can see that you use just a function name as a parameter in another function. So i am assuming that using function name is enough as using function pointer. Am i right ?

[minxomat]

VB6 is a completely different, no longer sold (but still supported) language from VB.NET (which the current version of is VB14). Pointers in VB6 are native pointers. What you need is exactly this:

4 hours ago, kcvinu said:

And in your example, i can see that you use just a function name as a parameter in another function. So i am assuming that using function name is enough as using function pointer. Am i right ?

Yes. I suggest you read the AutoIt Helpfile on that topic, which should make this clearer.