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
• TEdit (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 add paths to "sys.path". Must do only for Windows, for portable Python, don't do for Linux. I add paths: dir+'DLLs', dir+'python33.zip', dir+'Py' (dir is ExtractFilePath(Application.ExeName)).

 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: AnsiString;
   i: Integer;
 begin
   Str:= ;
   for i:= 0 to Length(Dirs)-1 do
     Str:= Str + SWideStringToPythonString(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;