# How to cast FARPROC! to Func\? **URL:** https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701 **Category:** Silver **Tags:** windows, silver **Created:** [March 7, 2018, 2:04am UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701 "2018-03-07T02:04:03Z") **Posts on this page:** 7 **Page:** 1
### Author: ![conio](https://talk.remobjects.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@conio](https://talk.remobjects.com/u/conio) #### Post date: [March 7, 2018, 2:04am UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/1 "2018-03-07T02:04:03Z")
I’m trying to load a DLL with `LoadLibrary`, get an export using `GetProcAddress` and call it. (This is basicaly the same problem as in [Calling functions exported by Dlls from Silver](https://talk.remobjects.com/t/calling-functions-exported-by-dlls-from-silver/15334)) The code looks something like: ``` var hSilverDLL1 = LoadLibrary("SilverDLL1.dll") var pFoo = GetProcAddress(hSilverDLL1, "_Foo@0"); var pFoo2 = pFoo as Func ``` This fails with: ``` error E559: Cannot safely cast "FARPROC!" to "Func" did you mean to use "as!"? error E129: Cannot cast from "FARPROC!" to "Func!" ``` Using `as!` doesn’t help. The first error disappears but the second remains. Trying to pass through `LPVOID` like this: ``` var pFoo = GetProcAddress(hSilverDLL1, "_Foo@0"); var pFoo2 = pFoo as! rtl.LPVOID var pFoo3 = pFoo2 as! Func ``` doesn’t work either: ``` error E129: Cannot cast from "LPVOID!" to "Func!" ``` (Using `as` rather than `as!` gives even more errors. like in the first excerpt.) The suggestion is the post I linked above doesn’t work for me. I can’t statically linked to the DLL. I need to load it at runtime and discover its exports at runtime. Am I missing some obvious way to perform this cast? (Using Elements 10.0.0.2255 on VS 2015 on Windows 10 x64, compiling x86 binaries.) ---
### Author: ![ck](https://talk.remobjects.com/user_avatar/talk.remobjects.com/ck/32/8740_2.png) [@ck](https://talk.remobjects.com/u/ck) #### Post date: [March 7, 2018, 7:37am UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/2 "2018-03-07T07:37:46Z")
See > [@Access Violation casting FARPROC to Any in Silver](https://talk.remobjects.com/t/access-violation-casting-farproc-to-any-in-silver/15702/2): > > The big problem here is that it shouldn’t allow this in the first place (same issue as [FARPROC to Func](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701)). Func and friends are “block” delegates, in that they capture a self pointer too and end up as a class (Delegate in Island/Echoes), which isn’t compatible with function pointers. We don’t currently have a syntax for function pointers in swift, but I see Swift now has one, so expect this one to work for fridays build: typealias MyFunc = @convention(c) () -\> Bool var pFoo = GetProcAddress(hSi… ---
### Author: ![mh](https://talk.remobjects.com/user_avatar/talk.remobjects.com/mh/32/18050_2.png) [@mh](https://talk.remobjects.com/u/mh) #### Post date: [March 7, 2018, 11:56am UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/3 "2018-03-07T11:56:05Z")
> [@ck](#): > > We don’t currently have a syntax for function pointers in swift, [FunctionPointer](https://docs.elementscompiler.com/API/Aspects/FunctionPointer/) doesn’t work in Swift/Island? ---
### Author: ![ck](https://talk.remobjects.com/user_avatar/talk.remobjects.com/ck/32/8740_2.png) [@ck](https://talk.remobjects.com/u/ck) #### Post date: [March 7, 2018, 12:28pm UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/4 "2018-03-07T12:28:14Z")
That works too. ---
### Author: ![conio](https://talk.remobjects.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@conio](https://talk.remobjects.com/u/conio) #### Post date: [March 8, 2018, 2:28am UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/5 "2018-03-08T02:28:18Z")
Maybe I’m doing something wrong but I can’t get it to compile. I’m doing something like (shamelessly adapted from the GUI sample): ```auto import rtl class Program { @FunctionPointer private typealias FooType = () -> (Bool) static let szTitle: LPCWSTR = "RemObjects Elements — Island Windows Sample" static let szWindowClass: LPCWSTR = "IslandWindowsSample" static var button: HWND = nil @CallingConvention(CallingConvention.Stdcall) static func WndProc(_ hWnd: HWND, _ message: UINT, _ wParam: WPARAM, _ lParam: LPARAM) -> Integer { switch message { case WM_COMMAND: if wParam == BN_CLICKED && lParam == button as! rtl.LPARAM { MessageBox(hWnd, "You clicked, hello there!", szTitle, 0) var x = true var hSilverDLL1 = LoadLibrary("SilverDLL1.dll") var pFoo = GetProcAddress(hSilverDLL1, "_Foo@0") var pFoo3 = pFoo as? FooType x = pFoo3() if (!x) { writeLn("fdg") } } ..... ``` I still get: `(E129) Cannot cast from "FARPROC!" to "Program.FooType?"` ---
### Author: ![ck](https://talk.remobjects.com/user_avatar/talk.remobjects.com/ck/32/8740_2.png) [@ck](https://talk.remobjects.com/u/ck) #### Post date: [March 8, 2018, 6:07am UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/6 "2018-03-08T06:07:45Z")
You need the upcoming beta (fridays) build. ---
### Author: ![conio](https://talk.remobjects.com/letter_avatar_proxy/v4/letter/c/c2a13f/32.png) [@conio](https://talk.remobjects.com/u/conio) #### Post date: [March 19, 2018, 10:55pm UTC](https://talk.remobjects.com/t/how-to-cast-farproc-to-func-somethingelse/15701/7 "2018-03-19T22:55:36Z")
Thanks. I’ll try it out as soon as it gets to the public stable channel. ~~Will I be needing both `@FunctionPointer` mentioned here **and** `@convention(c)` mentioned in the other post or will only one of them be enough?~~ Strike that. I see that in the other post you wrote that `@convention` alone should be enough.