problems with generation of c# wrapper for c++ function with function ptr argument

Carlos Frederico Biscaya <[email protected]> Wed, 19 Feb 2020 15:05:24 +0100

Newsgroups	gmane.comp.programming.swig
Message-ID	<CANWOLaahSod9c3UdoeAcUu6++T6sAmPpXoscpG=_UqFRqLqhOA@mail.gmail.com>

Hi guys,

I've started using swig a few months ago and after a few hickups had my
first functioning c# wrapper. Now I need to create a wrapper in C# that
wrapps a C++ function that takes a function ptr argument. I used a typedef
for the function ptr type and the swig macro cs_callback that I found while
researching how to get this done.

Unfortunatelly I seem to be stuck now.
AFAIK one of  two things should be happening, which aren't.

1) the delegate corresponding to my typedef for my function ptr is not
generated anywhere

typedef void (_stdcall *infobarObserverFunc)(InfoBarData*);

2) If I try using a typemap for inserting the delegate member into the
generated class, nothing happens.

I seem to be way out of my depth here and hope, someone can provide me with
some insight as to what is going wrong. I've attached a minimal example
that reproducibly gives me headaches and the swig project file needed. In
my development environment I am using swig 4.0.1.


I've tried using -E to see whether something suspicious show up after
preprocessing.

Best regards and thank you for your time,
Fred

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UiData.h (text/plain, 80 B)

#pragma once

extern "C" {

struct UiData 
{
	double temperature;
};

}

UiDataProvider.h (text/plain, 366 B)

#pragma once

#include "UiData.h"

typedef void (_stdcall *uiDataObserverFunc)(InfoBarData*);


#ifdef SYSTEMUI_EXPORTS
#define SYSTEMUI_API __declspec(dllexport)
#else
#define SYSTEMUI_API __declspec(dllimport)
#endif


extern "C" {

	SYSTEMUI_API void UI_Init();
				 
	SYSTEMUI_API void UI_RegisterObserver(uiDataObserverFunc callbackFunc);
}

UiModule_cs.i (text/plain, 1.3 KB)

#define SYSTEMUI_EXPORTS

%module UiWrapper

%define %cs_callback(TYPE, CSTYPE)
	%typemap(ctype) TYPE, TYPE& "void*"
	%typemap(in) TYPE  %{ $1 = ($1_type)$input; %}
	%typemap(in) TYPE& %{ $1 = ($1_type)&$input; %}
	%typemap(imtype, out="IntPtr") TYPE, TYPE& "CSTYPE"
	%typemap(cstype, out="IntPtr") TYPE, TYPE& "CSTYPE"
	%typemap(csin) TYPE, TYPE& "$csinput"
%enddef

%typemap(ctype) enum SWIGTYPE * "int *"
%typemap(imtype) enum SWIGTYPE * "out int"
%typemap(cstype) enum SWIGTYPE * "out $*csclassname"
%typemap(csin,
   pre="    int temp_$csinput = 0;",
   post="      $csinput = ($*csclassname)temp_$csinput;"
   ) enum SWIGTYPE *
   "out temp_$csinput"
%typemap(in) enum SWIGTYPE *
%{ $1 = ($1_ltype)$input; %}

%apply enum SWIGTYPE * {enum SWIGTYPE * const}

%rename("%(strip:[UI_])s") "";

%cs_callback(uiDataObserverFunc, cppUiDataObserverCallback)

%typemap(cscode) UiWrapper %{
	[UnmanagedFunctionPointerAttribute(CallingConvention.Cdecl)]
    public delegate void cppUiDataObserverCallback(UiData* uiDataUpdate);
%}

%{
#include "UiData.h"
#include "UiDataProvider.h"
%}

// these headers have to come before anything else - otherwise syntax error(1) will be thrown	
%include <windows.i>
%include <carrays.i>
%include <cpointer.i>

%include "UiData.h"
%include "UiDataProvider.h"