On 2016-07-14 11:31, Bo Berglund wrote:
>
> function TSSCommHandler.ZipFiles(TargetFile: string; FileList:
> TStringList): boolean;
> var
> ZW: TZipWrite;
> i: integer;
> FileName: string;
> begin
> Result := false;
> ZW := TZipWrite.Create(TargetFile);
I would replace that with a Factory Method call. For example:
var
lCompress: TCompressAbs;
...
begin
lCompress := gCompressFactory.CreateInstance(cZipWrite);
lCompress.OutputFile := 'something.zip';
for i := 0 to FileList.Count-1 do
lCompress.AddFile(FileList[i]);
So later when you want to switch to say TurboPower or ZLib, you simply
need to change one line.
lCompress := gCompressFactory.CreateInstance(cZLib);
or
lCompress := gCompressFactory.CreateInstance(cTPAbbrevia);
What I also do in my applications is to reduce that to a single
constant, so only one location (or compiler define) needs to change. I
do this always for database connections with tiOPF too.
eg:
-----------[ constants.pas ]-----------
const
{$IFDEF ZIPWRITE}
cCompress = cZipWrite;
{$ENDIF}
{$IFDEF ZLIB}
cCompress = cZLib;
{$ENDIF}
{$IFDEF ABBREVIA}
cCompress = cTPAbbrevia;
{$ENDIF}
then everywhere in my application I use the new constant
lCompress := gCompressFactory.CreateInstance(cCompress);
So now a simple single project wide compiler define change and
recompile, and my program will use a different compression component
suite throughout.
> Do you have an example of how to do the above with FPC ZLib?
Yes, and even a nice chapter on explaining it all.
http://tiopf.sourceforge.net/Doc/Concepts/6_TheAdaptorForDatabaseIndependence.shtml
See the following units in the tiOPF’s “tiopf2” branch:
Git repository:
https://sourceforge.net/p/tiopf/code/ci/tiopf2/tree/
Files:
Core/tiCompress.pas
Options/tiCompressNone.pas
Options/tiCompressZLib.pas
Regards,
Graeme
--
fpGUI Toolkit - a cross-platform GUI toolkit using Free Pascal
http://fpgui.sourceforge.net/
My public PGP key: http://tinyurl.com/graeme-pgp
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