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 needed

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>

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 special folder for my app, to put Py modules, so I can import them).

  procedure TfmMain.PythonEngineAfterInit(Sender: TObject);
  var
    SDir, S1, S2, S3: string;
  begin
    {$ifdef windows}
    SDir:= ExtractFilePath(Application.ExeName);
    S1:= SDir + 'DLLs';
    S2:= SDir + 'python33.zip';
    S3:= SDir + 'Py';
    Py_SetSysPath([S1, S2, S3]);
    {$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:

  procedure TfmMain.FormCreate(Sender: TObject);
  begin
    {$ifdef windows}
    PythonEngine.DllName:= 'python33.dll';
    {$endif}
    {$ifdef linux}
    PythonEngine.DllName:= 'libpython3.4m.so.1.0';
    {$endif}
    PythonEngine.LoadDll;
  end;