Using Python in Lazarus on Windows/Linux

Intro

I need to make app, cross platform, Win/Linux, which embeds Python engine. I tried Python4Delphi, but it doesn't compile and work on Linux x64. Same app must run on Win and Linux, must use portable Python 3 on Win and system Python 3 on Linux.

Result

Links

• modified Python4Delphi
• app

Work on Ubuntu 14.04 x64

Work on Windows7 x64

Modify P4D

Package "p4dlaz.lpk": delete all refs to units "...Delphi...". (Maybe units aren't needed for Lazarus apps.) Make modifications to PythonEngine.pas, see lines with "//AT". Compile and use package. You must see "Python" tab appeared in component pallette.

App

Files on Windows

On Windows you need to copy files to app folder. From "Sublime Text 3" installation for win, take Python files and copy them to app folder:

• python33.dll
• msvcr100.dll
• python33.zip
• .pyd files, to folder DLLs

Manifest on Windows: "appname.exe.manifest":

 <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
 <assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
   <noInheritable/>
   <assemblyIdentity
       type="win32"
       name="DelphiApplication"
       version="1.0.0.0" 
       processorArchitecture="*"/>
   <dependency>
     <dependentAssembly>
       <assemblyIdentity type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' processorArchitecture='*' publicKeyToken='6595b64144ccf1df' language='*' />
     </dependentAssembly>
   </dependency>
   <trustInfo xmlns="urn:schemas-microsoft-com:asm.v3">
     <security>
       <requestedPrivileges>
         <requestedExecutionLevel level='asInvoker' uiAccess='false' />
       </requestedPrivileges>
     </security>
   </trustInfo>
 </assembly>

Files on MacOSX

On Mac user needs to install Python: download Py 3.4 installer and install it. Full path to lib must be set in code, I could not init library w/out path. Example - in the code below.

App form

Put on form:

• TPythonEngine
• TPythonInputOutput
• TCombobox (edConsole)
• TMemo (memoConsole)

Props of PythonEngine:

• AutoLoad=False
• DllName empty
• DllPath empty
• FatalAbort=False
• InitScript="import sys; print('Python', sys.version)"
• IO=PythonInputOutput1
• PyFlags=[pfIgnoreEnvironmentFlag]
• UseLastKnownVersion=False

Event handlers

• PythonEngine.OnAfterInit: must set "sys.path". Only for Windows. I add paths: dir+'DLLs', dir+'python33.zip', dir+'Py' ("Py" is a special folder for my app, to put modules).

procedure TfmMain.PythonEngineAfterInit(Sender: TObject);
var
  dir: string;
begin
  {$ifdef windows}
  dir:= ExtractFilePath(Application.ExeName);
  Py_SetSysPath([
    dir + 'DLLs',
    dir + 'python33.zip',
    dir + 'Py'
    ]);
  {$endif}
end;

procedure Py_SetSysPath(const Dirs: array of string);
var
  Str: string;
  i: Integer;
begin
  Str:= '';
  for i:= 0 to Length(Dirs)-1 do
    Str:= Str + 'r"' + Dirs[i] + '"' + ',';
  Str:= Format('sys.path = [%s]', [Str]);
  GetPythonEngine.ExecString(Str);
end;

• PythonInputOutput.OnSendData, OnSendUniData:

procedure TfmMain.PythonInputOutput1SendData(Sender: TObject;
  const Data: AnsiString);
begin
  memoConsole.Lines.Add(Data);
end;

procedure TfmMain.PythonInputOutput1SendUniData(Sender: TObject;
  const Data: UnicodeString);
begin
  memoConsole.Lines.Add(Data);
end;

• edConsole.OnKeyPress:

procedure TfmMain.edConsoleKeyPress(Sender: TObject; var Key: char);
var
  Str: string;
begin
  if Key=#13 then
  begin
    Str:= edConsole.Text;

    //support entering "=some cmd"
    if (Str<>'') and (Str[1]='=') then
      Str:= 'print('+Copy(Str, 2, MaxInt) + ')';

    memoConsole.Lines.Add('>>> '+Str);
    edConsole.Text:= '';
    edConsole.Items.Insert(0, Str);
    try
      GetPythonEngine.ExecString(Str);
    except
    end;
  end;
end;

• main form OnCreate:

const
  cPyLibraryWindows = 'python33.dll';
  cPyLibraryLinux = 'libpython3.4m.so.1.0';
  cPyLibraryMac = '/Library/Frameworks/Python.framework/Versions/3.4/lib/libpython3.4.dylib';

procedure TfmMain.FormCreate(Sender: TObject);
var
  S: string;
begin
  S:=
    {$ifdef windows} cPyLibraryWindows {$endif}
    {$ifdef linux} cPyLibraryLinux {$endif}
    {$ifdef darwin} cPyLibraryMac {$endif} ;
  PythonEngine.DllPath:= ExtractFileDir(S);
  PythonEngine.DllName:= ExtractFileName(S);
  PythonEngine.LoadDll;
end;