Hello,

I'm having issues when trying to use the CreateThread WinAPI, and I hope someone here can assist me.
Seems like the callback function is never called for some reason, as the message box never shows, but CreateThread doesn't seem to fail.

Example code:

code:

---

var thread_id = Interop.Allocate(4);
var func = Interop.GetCallbackPtr("ExampleCallback");
var thread = Interop.Call("kernel32.dll", "CreateThread", null, 0, func, null, 0, thread_id);
if (!thread)
{
    Debug.Trace("Could not create thread.");
    return;
}

---

code:

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function ExampleCallback(Param)
{
    Interop.Call("user32.dll", "MessageBoxW", 0, "It works!", "", 0);
    return 1;
}

---

The GetCallbackPtr has to actually be a callback not one just defined by the user.

For instance MonitorEnumProc.

The reason for this is because Patchou had to define these functions within Messenger Plus! itself therefore it will not allow you to define a function and get a pointer to it.

I see. Thank you very much for your quick reply.

quote:

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Originally posted by matty
The reason for this is because Patchou had to define these functions within Messenger Plus! itself therefore it will not allow you to define a function and get a pointer to it.

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quote:

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Originally posted by Eljay
However, the reason the OP's code doesn't work is that CreateThread needs an asynchronous callback to work, and unfortunately, Plus! only supports synchronous callbacks due to technical limitations of the scripting engine.

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Wrong it fully supports asynchronous call backs. However because they are defined within Messenger Plus! each call to the same function will return the same pointer. Therefore 2 scripts calling the same pointer can cause issues. You cannot get a callback pointer to a function that hasn't been defined within Messenger Plus!.

We will discuss this later on MSN

Thanks, Eljay and matty.
Is it possible to accomplish this by moving the code into a DLL?

The way I see it, Plus! has one internal (native) function that is used as a callback. When you call GetCallbackPtr, Plus! stores the name of the function and the script engine object for the script that called it. This is why the callback must be used immediately and synchronously, because other scripts calling GetCallbackPtr would screw everything up.

Patchou did post somewhere a more technical explanation as to why he can't support asynchronous callbacks, but I can't find it

quote:

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Originally posted by Danny22
I guess I can accomplish this by moving the code into a DLL?
Thanks Eljay and matty.

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quote:

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Originally posted by Eljay
Most likely yes, maybe if you explained what you were trying to accomplish we can help out.

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matty and Eljay: you both are both wrong and right
CookieRevised's reply to [Resource] Subclassing ActiveXObjects (and [Release] TabbedStatusIcon too!)

I gave it a shot and made a simple example DLL.
It exports a function which calls CreateThread (the callback function is in the DLL, too, of course), which I can call in my script. Seems to work well.
Thanks, everyone!

quote:

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Originally posted by Mnjul
matty and Eljay: you both are both wrong and right
CookieRevised's reply to [Resource] Subclassing ActiveXObjects (and [Release] TabbedStatusIcon too!)

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I could be wrong, but my understanding about knowing if a function was called with the right number of arguments or not, is checking for a stack imbalance after the call, hence why the plus documentation says to only call functions with stdcall convention.

Edit: i just realised that what i said doesn't have much relevance...