How to use library from Delphi 10.1 DCUs in Delphi 10.3.3?

[PeterPanettone 158]

Unfortunately, I have a specific library for which I have only Delphi 10.1 Berlin DCUs (no source code), but I need to use this library in Delphi 10.3.3 Rio.

 

Which is the best strategy to achieve this? (DLLs, Packages, ...)

Edited January 27, 2020 by PeterPanettone

[David Heffernan 2353]

Build the dcus into a dll and link to that.

 

You can't use packages because you can only link packages that were compiled with the same compiler. 

 

That's a short term solution. Long term you should replace the library. 

[dummzeuch 1517]

... or get the source code.

[PeterPanettone 158]

16 hours ago, David Heffernan said:

That's a short term solution. Long term you should replace the library.

That is OBVIOUS.

[PeterPanettone 158]

17 hours ago, David Heffernan said:

Build the dcus into a dll and link to that.

Can you indicate me a practical example?

 

(There is no theory about the difference between theory and practice)

Edited January 28, 2020 by PeterPanettone

[David Heffernan 2353]

Start by following a tutorial on how to create a dll and export a simple function. Work up from there. 

[PeterPanettone 158]

Done. It works, but when I close the host exe it CRASHES. The exe also crashes on Close even if I don't press the button!

 

See attachment:

 

TestDLL.zip

Edited January 28, 2020 by PeterPanettone

[PeterPanettone 158]

16 minutes ago, PeterPanettone said:

when I close the host exe it CRASHES. The exe also crashes on Close even if I don't press the button!

After having removed ShareMem from the uses list in both the DLL and the host exe, it does not crash anymore!

[rvk 44]

You don't need LoadLibrary/FreeLibrary if you use a static function definition like "external myDLL". So use either LoadLibrary/GetProcAddress/FreeLibrary or use function/external myDLL.

 

Also... you use a string as parameter. That is a managed type. I'm not sure but that might give you problems.

 

[PeterPanettone 158]

28 minutes ago, rvk said:

You don't need LoadLibrary/FreeLibrary if you use a static function definition like "external myDLL". So use either LoadLibrary/GetProcAddress/FreeLibrary or use function/external myDLL.

 

Also... you use a string as parameter. That is a managed type. I'm not sure but that might give you problems.

 

I have changed the code using PWideChar now:

 

DLL:

 

function JclShell_DisplayPropDialog(AHandle: THandle; AFile: PWideChar): Boolean; stdcall;
begin
  Result := JclShell.DisplayPropDialog(AHandle, string(AFile));
end;

 

Host exe:

 

function JclShell_DisplayPropDialog(AHandle: THandle; AFile: PWideChar): Boolean; stdcall; external myDLL;

procedure TForm3.btnTestClick(Sender: TObject);
begin
  if JclShell_DisplayPropDialog(0, PWideChar(edtFile.Text)) then
    Self.Caption := 'Success'
  else
    Self.Caption := 'Failure';
end;

 

It does work well, no crash. 

[aehimself 399]

On 1/27/2020 at 7:30 PM, David Heffernan said:

Build the dcus into a dll and link to that.

This is a ridiculously perfect and simple idea. Fortunately I have source for everything, but I'll keep this in my mind for later!

[Lars Fosdal 1793]

It is a good way of black-boxing old code.

The drawback of using DLLs is that versioning the interface becomes important.

 

Want to add a parameter to a function? 

It will break the compatibility with the old DLL, so better to add a second function.

 

Want to change a structure?

Another break - unless you planned for it and have structure versioning and size info, and always add content at the end of the structure.

 

Win32 is jam-packed with the above.