How Define Callback Func Inside Of Calling Method?

Question

I would like to declare / define my delegate and callback function inside of the calling method. Is that possible ? If yes how ? This is my code that I want to execute my first implant operation on:

delegate bool myDelegate(IntPtr module, string type, IntPtr lParam);

public static bool EnumResTypeProc(IntPtr module, string typename, IntPtr lParam)
{
    (((GCHandle) lParam).Target as List<string>).Add(typename);
    return true;
}

public static string[] getResourceTypes(IntPtr module)
{
    List<string> result = new List<string>();
    GCHandle pin = GCHandle.Alloc(result);
    WinApi.EnumResourceTypes(module, Marshal.GetFunctionPointerForDelegate(new myDelegate(EnumResTypeProc)), (IntPtr)pin);
    pin.Free();
    return result.ToArray();
}

The closest I get:

delegate bool myDelegate(IntPtr module, string type, IntPtr lParam);

public static string[] getResourceTypes(IntPtr module)
{
    List<string> result = new List<string>();
    GCHandle pin = GCHandle.Alloc(result);
    myDelegate d = delegate(IntPtr handle, string typename, IntPtr lParam)
        { (((GCHandle) lParam).Target as List<string>).Add(typename); return true; };
    WinApi.EnumResourceTypes(module, Marshal.GetFunctionPointerForDelegate(d), (IntPtr) pin);
    pin.Free();
    return result.ToArray();
}

Declaring the delegate inside a method is not possible at this point. Even if compiled it causes unmanaged code to crash my application.

nawfal · Accepted Answer · 2013-07-15 12:09:38Z

2

Yes, you can use an anonymous method or a lambda expression.

// untested
Func<IntPtr, string, IntPtr, bool> inline = (module, typename, lParam) =>
{
    (((GCHandle)lParam).Target as List<string>).Add(typename);
    return true;
};

WinApi.EnumResourceTypes(module, Marshal.GetFunctionPointerForDelegate(inline), (IntPtr)pin);

edited Jul 15, 2013 at 12:09

nawfal

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answered Jul 15, 2013 at 11:57

Henk Holterman

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9 Comments

nawfal Over a year ago

I would avoid the type specification along with parameters. LHS would do it, isnt it?

Bitterblue Over a year ago

Looks promising. But doesn't work. First Action must be Func. Then compilation ok, but crashes at the call. Not sure but keyword delegate is needed ?

Henk Holterman Over a year ago

Well, like I said: untested. You voided the warranty by running it.

Bitterblue Over a year ago

@nawfal see original post + edit. Both versions work fine. Trying to declare the delegate inside of my method seems to cause crashes.

Bitterblue Over a year ago

@nawfal I'll try it. Maybe important: App crashes in unmanaged code. So I don't get an exception.

|

user2319884 · Accepted Answer · 2013-07-15 12:06:01Z

0

Try to use this links:

microsoft support

How to write callbacks in C# and .NET

answered Jul 15, 2013 at 12:06

user2319884

11 bronze badge

Comments

user2319884 · Accepted Answer · 2013-07-15 12:12:33Z

0

Or my example:

public delegate void AsyncMethodCaller(strind inputdata);


 void someMethod()
{
//
// ... some actions 
//
AsyncMethodCaller caller = new AsyncMethodCaller(this.ProcessInputData);

   // Initiate the asychronous call.
   IAsyncResult result = caller.BeginInvoke("my data");
}

void ProcessInputData(string inputData)
{
    // some actions
}

answered Jul 15, 2013 at 12:12

user2319884

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