pyscripter

Something like:

var SL := TStringList.Create;
try
  SL.LoadFromFile('__main__.py');
  GetPythonEngine.ExecStrings(SL);
  Mainmodule.run_settings();
finally 
  SL.Free;
end;

You can use LockUndo to disable Undo altogether.

LockUndo/UnlockUndo is also useful when you read a file or initially setup a text buffer.  If the Undo buffer is not empty then you would want to call ClearUndo before or after.

Assuming you are using the Turbopack Synedit:

Changes to the text buffer are undoable.   So just calling Delete does not clear all related memory.    You need to do one of:

• call ClearUndo every now and then to release the undo/redo memory.
• Set MaxUndo to some number to limit the undoable actions.  The default is 0 (unlimited undo/redo).
• call LockUndo/Unlock undo to prevent actions being added to the undo/redo stack (the most efficient).

If you still get a memory overflow then this is a bug that you should report.

I had a similar issue.   If I remember well, setting the ParentBackground property to true for all controls helped, although I see in the previous thread that @Uwe Raabe claimed the opposite.

There was such an issue https://quality.embarcadero.com/browse/RSP-31158 that is supposed to be fixed in D11.   See also the related issues to this one.

See also TStyleManager.UseParentPaintBuffers introduced in D11.   I have not tried it and there is limited documentation.

You are not calling PythonEngine1.Load.
Demo34 shows how to load a python engine dynamically, but please note that this is very tricky and things can go wrong.

Python4Delphi demo33 (multithread) does not work · Issue #373 · pyscripter/python4delphi (github.com) is now fixed.  

TPythonEngine and TPyDelphiWrapper are singleton.  You should not have two in the same application.   Better to add your control wrapper to delphivcl and recompile.

In using delphivcl.pyd  the user can attach an arbitrary python method as an event handler to any vcl component at runtime.   The event handler needs to be created on-the-fly, since you do not know in advance what python method will attach to which events.   TMethodImplementation can do just that.  Create an event handler of the right type when it is need.  In this use case the callback would translate the Args to their python equivalents and call the python code.

The callback can be an anonymous method, but this is not important.  The important thing is that the event handler needs to be created at runtime and not at compile time.  Currently  python4delphi needs to provide helper classes for each event type (TNotifyEventHandler for TNotifyEvent etc.).  All this code can go away and have just one generic implementation of event handling that can deal with any kind of event.

For example in the code below:

class MyForm(Form):
    def __init__(self, owner):
        self.timer = Timer(self)
        self.timer.Interval = 10
        self.timer.OnTimer = self.__on_timer
        self.timer.Enabled = True

    def __on_timer(self, sender):
        self.CheckBox1.Enabled = True

when self.timer.OnTimer = self.__on_timer is executed an event handler needs to be attached to the OnTimer event of a Delphi timer object that will run the python method.

1 hour ago, Dave Novo said:

While technically this seems cool, why is this particularly useful? I see that I can create an event handler without an explicit object that will implement the event handler method. Why would I need to do this?

 

Did you read my first post?  It answers your question providing some use cases.  Spring4d also uses this for supporting multicast events.

Here is an example of making an event handler on the fly using spring4d, TMethodImplementation and a callback routine, in case anyone has a use for it.

program MethodImplementationTest2;
{$APPTYPE CONSOLE}
{$R *.res}

uses
  System.SysUtils,
  System.TypInfo,
  System.Rtti,
  Spring;

type
  TSimpleEvent = function(I: Integer): Integer of object;

  TTestClass = class
  private
    fEvent: TSimpleEvent;
  published
    property Event: TSimpleEvent read fEvent write fEvent;
  end;

procedure ImplCallback(UserData: Pointer; const Args: TArray<TValue>;
    out Result: TValue);
begin
  WriteLn('From Implementation');
  WriteLn(Args[0].AsObject.ClassName);
  Result := Args[1].AsInteger * 2;
end;

begin
  ReportMemoryLeaksOnShutdown := True;
  var TestObj := Shared.Make(TTestClass.Create)();
  try
    var RTTIContext := TRttiContext.Create;
    var RTTIType := RTTIContext.GetType(TypeInfo(TTestClass));
    var RTTIMethodType := RTTIType.GetProperty('Event').PropertyType;

    var MethodImplementation := (RTTIMethodType as TRttiInvokableType).CreateImplementation(nil, ImplCallback);
    var Method: TMethod;
    Method.Code := MethodImplementation.CodeAddress;
    Method.Data := TestObj;
    SetMethodProp(TestObj, 'Event', Method);

    WriteLn(TestObj.Event(2));
    MethodImplementation.Free;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
  ReadLn;
end.

Output:

From Implementation
TTestClass
4

Feature request submitted: [RSP-38690] Add CreateImplementation method for TRttiInvokableType - Embarcadero Technologies

System.Rtti contains a lesser known, but powerful class TMethodImplementation, which is basically hidden and used in TVirtualMethodInterceptor.  Outside this use, it cannot be created directly and it can only be accessed by TRttiMethod.CreateImplementation.   

I recently discovered that Spring4d extends its use through a helper for TRttiInvokableType, so it can be used with standalone procedures and functions as well as with events.  Here is a small console app showing how it can be used:

program MethodImplementationTest;
{$APPTYPE CONSOLE}
{$R *.res}

uses
  System.SysUtils,
  System.TypInfo,
  System.Rtti,
  Spring;

type
  TSimpleProc = function(I: Integer): Integer;

procedure ImplCallback(UserData: Pointer; const Args: TArray<TValue>;
    out Result: TValue);
begin
  WriteLn('From Implementation');
  Result := Args[0].AsInteger * 2;
end;

var
  Proc: TSimpleProc;
begin
  ReportMemoryLeaksOnShutdown := True;
  try
    var RTTIContext := TRttiContext.Create;
    var RTTIType := RTTIContext.GetType(TypeInfo(TSimpleProc));
    var ProcImplementation := (RTTIType as TRttiInvokableType).CreateImplementation(nil, ImplCallback);

    Proc := TSimpleProc(ProcImplementation.CodeAddress);

    WriteLn(Proc(2));
    ProcImplementation.Free;
  except
    on E: Exception do
      Writeln(E.ClassName, ': ', E.Message);
  end;
  ReadLn;
end.

Output:

From Implementation
4

Simple and easy.  Spring4D is full of gems.  I wish the above functionality was part of the standard library.

I can think of many uses:

• Python4Delphi contains a unit MethodCallback which uses complex assembly to convert methods into stubs that can be used with external C libraries.  It could be rewritten using TMethodImplementation, without assembly code.
•  Also in Python4Delphi, the implementation of Delphi events using python code could be very much simplified and generalized using TMethodImplementation.  You can create Delphi functions, procedures and methods, event handlers on the fly that are implemented by python code.
• Similarly functionality can be provided with other scripting languages.

This was due to a bug (TPyDelphiObject.SetAttrO causes memory leak · Issue #368 · pyscripter/python4delphi (github.com)) which is now fixed.   

It may take some time for the fix to be reflected in the pip installable delphivcl, but you can always compile your own delphivcl.pyd from the github sources.

@shineworldThanks for discovering the issue.

Just to clarify.   

a)  No memory leakage happens if your timer routine is:

    def __on_timer(self, sender):
        pass

b)  The increase in memory usage increases indefinitely when self.CheckBox1.Enabled = True is called inside the timer routine.

c) Could this be tracemalloc overhead?   (the memory traces take memory space).  For example does the memory gets released with 

tracemalloc.clear_traces()  (tracemalloc — Trace memory allocations — Python 3.10.5 documentation)

d) Do you see Windows memory allocated to the process increasing without tracemalloc

I am not sure what is the problem you are trying to solve.

Your "Second attempt" should work.

In your "First attempt"

 myV := PythonModule1.GetVarAsVariant('myboxes');

fails because PythonModule1 has no variable 'myboxes'.   myboxes will be part of the main module namespace after your code gets executed.

GetVarAsVariant can be improved to avoid the access violation.

function  TPythonModule.GetVarAsVariant( const varName : AnsiString ) : Variant;
var
  obj : PPyObject;
begin
  CheckEngine;
  with Engine do
    begin
      obj := GetVar( varName );
      if Assigned(obj) then
        try
          Result := PyObjectAsVariant( obj );
        finally
          Py_XDecRef(obj);
        end;
    end;
end;

  for var V in VarPyIterate(MainModule.myboxes) do

V will be a python variant pointing to whatever is inside myboxes.

  Listbox1.items.add(V);

The above converts the python variant to string.

You can use either VarPy or the low-level python API to manipulate python tuples (e.g PyTuple_GetItem, PyTuple_SetItem etc.)

with VarPyth the unit tests give you a good idea of things you can do:

  c := VarPythonCreate([1, 2, 3, 4], stTuple); // test a tuple
  Assert.IsTrue( VarIsPythonTuple(c) );
  Assert.IsTrue( VarIsPythonSequence(c) );
  Assert.IsTrue( c.GetItem(1) = 2 );
  Assert.IsTrue( c.Length = 4 );
  c := NewPythonTuple(3);
  c.SetItem(0, 1);
  c.SetItem(1, 2);
  c.SetItem(2, 3);
  Assert.IsTrue( VarIsPythonTuple(c) );
  Assert.IsTrue( VarIsPythonSequence(c) );
  Assert.IsTrue( c.GetItem(1) = 2 );
  Assert.IsTrue( c.Length = 3 );

from python4delphi/VarPythTest.pas at master · pyscripter/python4delphi (github.com) 

The function return value is a tuple containing your lists.

Args is a tuple not a dictionary.  Search in the P4D source code for  PyArg_ParseTuple to see how to make use of Args.  There are hundreds of examples!

np_array.SetItem(0) 

should work.

From VarPyth source code:

          // here we handle a special case: COM (or Delphi?) doesn't allow you to have index properties
          // on a variant except from a true array variant! So if myVar is a Python variant that holds
          // a Python list, I can't write something like: myVar[0]! But if the list is a member of a
          // Python instance, it will work fine! Like: myInst.myList[0]
          // So, to handle this problem we detect some special names: GetItem, SetItem and Length
          // that will do the same as:
          // myList[0] <-> myList.GetItem(0)
          // myDict['Hello'] := 1 <-> myDict.SetItem('Hello', 1)
          // len(myList) <-> myList.Length()
          // we get some bonus with the slices and in operators also:
          // myList = [0, 1, 2, 3]; myList.GetSlice(1, 2) --> [1, 2]
          // myList.Contains(2) <-> 2 in myList

Have you seen python4delphi/Tutorials/Webinar II at master · pyscripter/python4delphi (github.com)?  The VarPyth demo shows how to work with numpy arrays (two way link).

4 hours ago, David Hoyle said:

guessing but I expect it uses the RTL code for regex

indeed.

Study demo 33 on how to interrupt a running python thread.  (TSortThread.Stop).

4 minutes ago, dummzeuch said:

Who is resposible for updating  SynEdit in Getit? Embarcadero?

Yes. 

SynEdit has been updated since these demos have been created.  I am not sure what version of SynEdit you are using, but the solution to such problems is to open the unit with the form in the IDE ignoring all errors and then save the unit again.