[fpc-pascal] Porting code from Windows D2007, missing Windows functions

[Michael Van Canneyt]

On Thu, 14 Jul 2016, Bo Berglund wrote:

> On Thu, 14 Jul 2016 10:09:36 +0100, Graeme Geldenhuys
> <mailinglists at geldenhuys.co.uk> wrote:
>
>> If you have the time, it might be worth abstracting out the zip reading
>> functionality so you can swap out the actual compression components used
>> as needed. This will allow your application to change compression tools
>> in future, without your application code needing any changes. This is
>> always a good design philosophy when it comes to using 3rd party components.
>>
>> While working at a previous employer we use the TurboPower suite of
>> compression components under Windows and Linux with great success, but
>> could also swap it out for the FPC included ZLib unit.
>>
>
> Well,
> I do have the zip *writing* in one single place as a method for the
> class that handles the communication. It gets a target zipfile name
> and a stringlist containing the files to zip as arguments, so that is
> pretty portable.
>
> Here is how it looks like:
>
> uses PasZip;
>
> function TSSCommHandler.ZipFiles(TargetFile: string; FileList:
> TStringList): boolean;
> var
>  ZW: TZipWrite;
>  i: integer;
>  FileName: string;
> begin
>  Result := false;
>  ZW := TZipWrite.Create(TargetFile);
>  try
>    try
>      for i := 0 to FileList.Count-1 do
>      begin
>        FileName := FileList[i];
>        if not FileExists(FileName) then Continue;
>        ZW.AddDeflated(FileName);
>      end;
>      Result := true;
>    except
>      on E: Exception do
>      begin
>        FLastError := 'Zip error: ' + E.Message;
>        exit;
>      end;
>    end;
>  finally
>    ZW.Free;
>  end;
> end;
>
> What I need elsewhere in the code is not depening on PasZip, the call
> to create the zipfile is simply:
>
> ZipFiles(TargetFile, FileList);
>
> So with the proper set of conditionals I could have different
> implementations of this method for Windows and Linux.
>
> Do you have an example of how to do the above with FPC ZLib?

You can find this almost verbatim in the examples of paszlib, using the
zipper unit.

Michael.