0

我正在使用 Python 3.8 和 Delphi 10.4.2。

我正在尝试使用Python4Delphi的组件通过 Python 脚本访问 Delphi 中定义的一些接口。

在设计时，我将 TPythonEngine、TPythonModule 和 TPyDelphiWrapper 组件添加到我的项目的 VCL 表单中。

所以我定义了3个接口，分别由3个类实现，如下

type
  IPerson = interface (IUnknown)
    ['{1D21B5B6-25DE-4884-8BDB-8E2D9A239D64}']
    function GetName : string;
    procedure SetName ( value : string );
    property Name: string read GetName write SetName;   
    function GetSurname: string;
    procedure SetSurname(value : string);
    property Surname : string read GetSurname write SetSurname;    
    function GetInfo : string;
  end;

  ICustomer = interface (IPerson)
    ['{8742364C-33E8-4FF4-86FB-C19AF67A735B}']
    function GetCustomerNumber : string;
    procedure SetCustomerNumber ( value : string );
    property CustomerNumber : string read GetCustomerNumber write SetCustomerNumber;
  end;

  ISupplier = interface ( IPerson )
    ['{420FFF78-92DE-4D7E-9958-FDA95748EEB7}']
    function GetSupplierNumber : string;
    procedure SetSupplierNumber ( value : string );
    property SupplierNumber : string read GetSupplierNumber write SetSupplierNumber;
  end;

  TPerson = class ( TInterfacedObject , IPerson)
  private
    FName : string;
    FSurname : string;    
    function GetName : string;
    procedure SetName ( value : string );    
    function GetSurname: string;
    procedure SetSurname(value : string);

  public
    property Surname : string read GetSurname write SetSurname;
    property Name: string read GetName write SetName;    
    function GetInfo : string; virtual;
  end;


  TCustomer = class ( TPerson , ICustomer)
  private
    FCustomerNumber : string;
    function GetCustomerNumber : string;
    procedure SetCustomerNumber ( value : string);

  public    
    property CustomerNumber : string read GetCustomerNumber write SetCustomerNumber;
    function GetInfo: string; override;
  end;


  TSupplier = class ( TPerson , ISupplier)
  private
    FSupplierNumber : string;
    function GetSupplierNumber : string;
    procedure SetSupplierNumber ( value : string );

  public
    property SupplierNumber : string read GetSupplierNumber write SetSupplierNumber;
    function GetInfo : string; override;
  end;

在表单的 Create 方法中，我定义了 3 个变量，为 3 个接口中的每一个定义一个，并通过 PyDelphiWrapper 我将它们传递给 Python 模块中的 3 个不同的 Python 变量。

procedure TFrmTestInterface.FormCreate(Sender: TObject);
var
  LPerson : IPerson;
  LCustomer : ICustomer;
  LSupplier : ISupplier;
  Py: PPyObject;
begin

  LPerson := TPerson.Create;
  LCustomer := TCustomer.Create;
  LSupplier := TSupplier.Create;

  LPerson.Name := 'Pippo';
  LPerson.Surname := 'Rossi';

  LCustomer.Name := 'Pluto';
  LCustomer.Surname := 'Verdi';

  LSupplier.Name := 'Paperino';
  LSupplier.Surname := 'Bianchi';


  Py := PyDelphiWrapper1.WrapInterface(TValue.From(LPerson));
  PythonModule1.SetVar('delphi_person', Py);
  GetPythonEngine.Py_DecRef(Py);

  Py := PyDelphiWrapper1.WrapInterface(TValue.From(LCustomer));
  PythonModule1.SetVar('delphi_customer', Py);
  GetPythonEngine.Py_DecRef(Py);

  Py := PyDelphiWrapper1.WrapInterface(TValue.From(LSupplier));
  PythonModule1.SetVar('delphi_supplier', Py);
  GetPythonEngine.Py_DecRef(Py);

end;

在运行时变量被正确解释，但每次我尝试访问接口中定义的属性之一时，我总是得到相同的错误。

这是我尝试运行的 Python 脚本：

from delphi_module import delphi_person, delphi_customer, delphi_supplier 

print('type(delphi_person) = ', type(delphi_person)) 
print('type(delphi_customer) = ', type(delphi_customer)) 
print('type(delphi_supplier) = ', type(delphi_supplier)) 

print(delphi_person.Name)

我得到的错误

回溯（最后一次调用）：文件“”，第 7 行，在 AttributeError 中：获取属性“名称”时出错。错误：未知属性

type(...) 命令对三个变量正确运行。

如果我不使用接口类型的 3 个变量，而是使用 PyDelphiWrapper.Wrap 方法将每个变量声明为类类型，那么一切正常！

procedure TFrmTestInterface.FormCreate(Sender: TObject);
var
  LPerson : IPerson;
  LCustomer : ICustomer;
  LSupplier : ISupplier;
  Py: PPyObject;
begin

  LPerson := TPerson.Create;
  LCustomer := TCustomer.Create;
  LSupplier := TSupplier.Create;

  LPerson.Name := 'Pippo';
  LPerson.Surname := 'Rossi';

  LCustomer.Name := 'Pluto';
  LCustomer.Surname := 'Verdi';

  LSupplier.Name := 'Paperino';
  LSupplier.Surname := 'Grandi';


  Py := PyDelphiWrapper1.Wrap(LPerson, TObjectOwnership.soReference);
  PythonModule1.SetVar('delphi_person', py);
  GetPythonEngine.Py_DECREF(py);

  Py := PyDelphiWrapper1.Wrap(LCustomer, TObjectOwnership.soReference);
  PythonModule1.SetVar('delphi_customer', py);
  GetPythonEngine.Py_DECREF(py);

  Py := PyDelphiWrapper1.Wrap(LSupplier, TObjectOwnership.soReference);
  PythonModule1.SetVar('delphi_supplier', py);
  GetPythonEngine.Py_DECREF(py);

end;

使用相同的 Python 脚本，我得到正确的输出而没有错误

在此处输入图像描述

任何人都知道我在使用 TPyDelphiWrapper 为 Python 脚本包装接口类型变量时做错了什么？

4

1 回答 1

0

Delphi does not add RTTI on properties defined in interfaces. Therefore property 'Name' cannot be found by the Python engine. RTTI is available for the methods when you add {$M+} before the interface declaration. Calling delphi_person.GetName() should work then.

There is another issue with using interfaces and the Python engine, the interface is not locked when you call WrapInterface. Therefore the object will be released when it goes out of scope.

于 2021-10-14T06:33:49.770 回答