Lazarus

Free Pascal => Windows => Topic started by: JohnRambo on September 20, 2017, 08:16:49 pm

Title: Using C# DLL in Lazarus
Post by: JohnRambo on September 20, 2017, 08:16:49 pm

At first I admit that in C # I am green like chives. I want to prepare a C# DLL using the UnmanagedExports tool (https://www.nuget.org/packages/UnmanagedExports (https://www.nuget.org/packages/UnmanagedExports)) in the C # DLL. Here's an example by author:https://stackoverflow.com/a/2055508/1919267 (https://stackoverflow.com/a/2055508/1919267) .
So far ok, managed to produce a DLL and use it in Delphi. But there is a problem: when I want to use the same file in Lazarus, it returns nothing. The code:

Code: Pascal  [Select][+][-]

1. var
2.   adder : IDotNetAdder;
3. begin
4.   try
5.    CreateDotNetAdder(adder);
6.    Writeln('4 + 3 = ', adder.Add3(4));

  returns me 0 (so I am thinking that DLL response  is nil). Is there any solution to fix that? Should I need to fix my pascal code or fix that DLL?

Title: Re: Using C# DLL in Lazarus
Post by: avra on September 21, 2017, 11:11:38 am

Next time you cross post I will hold my comments...  >:(
Please do not cross post in the future.  ;D

Title: Re: Using C# DLL in Lazarus
Post by: tudi_x on September 21, 2017, 11:30:25 am

@avra - the deletion of posts does not seem to work. maybe he opened a new one due to code not inserted as recommended in the first place.

@rambo - i think you need to have a handler for the dll and define the external function, something like

Code: Pascal  [Select][+][-]

1. TGetDeviceInfo = function(AIndex: integer): PTDeviceInfoRecord; cdecl;

after you define the handler and the function you can use it.

Title: Re: Using C# DLL in Lazarus
Post by: JohnRambo on September 21, 2017, 03:30:21 pm

Sorry for double topic but I can't delete topic in wrong category. I cant use COM, because I need to use old version of Lazarus (without ActiveX).
In my code I declare procedure in static way:

Code: Pascal  [Select][+][-]

1. var
2.   Form1: TForm1;
3.  procedure createdotnetadder(out instance:IDotNetAdder); stdcall external 'DelphiNETstd.dll' name 'createdotnetadder';
4. implementation
5. { TForm1 }

When I try to do it dynammicaly nothing work, only more problems. I don't understand that Delphi do it perfectly, but Lazarus not. In attachments I put .dll file and my pas unit. I don't asking about do it for me but to show me the way

Title: Re: Using C# DLL in Lazarus
Post by: JohnRambo on September 21, 2017, 04:53:56 pm

OK I made it. :D
Firstly we need to get some information: https://stackoverflow.com/a/9353800
"In C#/C++ you will need to define the Result as out Parameter, in order to maintain binary code compatibility of stdcall calling conventions" - thats the key. In my C# code I was use return. For Delphi its ok, but for Lazarus it is problematic. So I retyped my c# code from:

Code: C#  [Select][+][-]

1.    [ComVisible(true)]
2.     [ClassInterface(ClassInterfaceType.None)]
3.     public class DotNetAdder : DelphiNET.IDotNetAdder
4.     {
5.         public void Add3(int left)
6.         {
7.             return= left + 3;
8.            
9.         }
10.     }

to

Code: C#  [Select][+][-]

1.    [ComVisible(true)]
2.     [ClassInterface(ClassInterfaceType.None)]
3.     public class DotNetAdder : DelphiNET.IDotNetAdder
4.     {
5.         public void Add3(int left,out int result)
6.         {
7.             result= left + 3;
8.            
9.         }
10.     }

And change my pascal code from:

Code: Pascal  [Select][+][-]

1. //interface:
2.   type
3.   IDotNetAdder = interface
4.   ['{ACEEED92-1A35-43fd-8FD8-9BA0F2D7AC31}']
5.     function Add3(left : integer):integer; stdcall;
6.   end;
7.  
8. //execution:
9. var
10.   adder : IDotNetAdder;
11. begin
12.   try
13.    CreateDotNetAdder(adder);
14.    Writeln('4 + 3 = ', adder.Add3(4));

to

Code: Pascal  [Select][+][-]

1.  
2. //interface:
3.   type
4.   IDotNetAdder = interface
5.   ['{ACEEED92-1A35-43fd-8FD8-9BA0F2D7AC31}']
6.     function Add3(left : integer;out result:integer); stdcall;
7.   end;
8.  
9. //execution:
10.  CreateDotNetAdder(adder);
11.    i:=4;
12.    finally
13.    adder.Add3(i,x);
14.   showmessage('4 + 3 = '+ (inttostr(x)));
15.  

Title: Re: Using C# DLL in Lazarus
Post by: Cyrax on September 21, 2017, 05:01:54 pm

Code: Pascal  [Select][+][-]

1. void Add3(int left)

translates to

Code: Pascal  [Select][+][-]

1. procedure Add3(left:integer)

If you want result from your subroutine, you need to change C# code to

Code: Pascal  [Select][+][-]

1. int Add3(int left)

and Pascal version to

Code: Pascal  [Select][+][-]

1. function Add3(left:integer) : integer