python中什么是经典类和新式类

在Python 2.x版本中，有经典类和新式类的区别。经典类是指没有继承object类的类，而新式类则是继承了object类的类。在Python 3.x版本中，所有的类都默认继承自object类，因此不再有经典类和新式类的区别。

经典类和新式类的区别在于它们的方法解析顺序(MRO)不同。MRO是指在多重继承中，解释器查找方法的顺序。在经典类中，MRO是按照深度优先的顺序进行查找的，而在新式类中，MRO是按照广度优先的顺序进行查找的。这意味着在新式类中，父类的方法会优先于子类的方法被调用。

下面是一个经典类和新式类的示例：

# 经典类
class A:
    def foo(self):
        print("A")

class B(A):
    pass

class C(A):
    def foo(self):
        print("C")

class D(B, C):
    pass

d = D()
d.foo() # 输出：A

# 新式类
class A(object):
    def foo(self):
        print("A")

class B(A):
    pass

class C(A):
    def foo(self):
        print("C")

class D(B, C):
    pass

d = D()
d.foo() # 输出：C

相关问题

python的新式类和经典类的区别是什么

在 Python 2.x 版本中，有两种不同的类：经典类和新式类。而在 Python 3.x 版本中，只有一种类，即新式类。

经典类是指没有继承自任何类的类，而新式类则是继承自 object 类的类（或其子类）。在 Python 2.x 版本中，如果一个类没有显式地继承自 object 类，则它被认为是经典类；而在 Python 3.x 版本中，所有的类都默认继承自 object 类，因此都是新式类。

除了继承自 object 类之外，新式类还有一些其他的优点，例如支持新的描述符协议、属性等。此外，在多重继承中，新式类的方法解析顺序（MRO）更加合理，可以避免经典类中的一些问题。

因此，为了充分利用 Python 中的一些新特性，一般建议使用新式类。在 Python 3.x 版本中，由于所有的类都默认继承自 object 类，因此不需要特别声明一个类是新式类。而在 Python 2.x 版本中，可以通过在类定义时显式继承自 object 类来声明一个类是新式类。例如：

class MyClass(object):
    pass

在 Python2.x 中，定义类时需要继承自 object，这是因为在 Python2.x 中，类可能会继承自经典类(classic class)或新式类(new-style class)，而继承自 object 就是为了定义新式类。新式类在 Python2.x 中引入了许多新功能，比如属性访问控制、静态方法和类方法等 举例说明 加不加object的区别

下面举一个简单的例子来说明在 Python2.x 中，继承自 `object` 和不继承自 `object` 的区别：

# 继承自 object 的新式类
class NewStyleClass(object):
    def method(self, handles)
% hObject    handle to b_edit (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end


function c_edit_Callback(hObject, eventdata, handles)
% hObject    handle to c_edit (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of c_edit as text
%        str2double(get(hObject,'String')) returns contents of c_edit as a double


% --- Executes during object creation, after setting all properties.
function c_edit_CreateFcn(hObject, eventdata, handles)
% hObject    handle to c_edit (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end


function d_edit_Callback(hObject, eventdata, handles)
% hObject    handle to d_edit (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of d_edit as text
%        str2double(get(hObject,'String')) returns contents of d_edit as a double


% --- Executes during object creation, after setting all properties.
function d_edit_CreateFcn(hObject, eventdata, handles)
% hObject    handle to d_edit (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: edit controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end


% --- Executes on selection change in curve_type_popupmenu.
function curve_type_popupmenu_Callback(hObject, eventdata, handles)
% hObject    handle to curve_type_popupmenu (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns curve_type_popupmenu contents as cell array
%        contents{get(hObject,'Value')} returns selected item from curve_type_popupmenu


% --- Executes during object creation, after setting all properties.
function curve_type_popupmenu_CreateFcn(hObject, eventdata, handles)
% hObject    handle to curve_type_popupmenu (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end


% --- Executes on selection change in surface_type_popupmenu.
function surface_type_popupmenu_Callback(hObject, eventdata, handles)
% hObject    handle to surface_type_popupmenu (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: contents = cellstr(get(hObject,'String')) returns surface_type_popupmenu contents as cell array
%        contents{get(hObject,'Value')} returns selected item from surface_type_popupmenu


% --- Executes during object creation, after setting all properties.
function surface_type_popupmenu_CreateFcn(hObject, eventdata, handles)
% hObject    handle to surface_type_popupmenu (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    empty - handles not created until after all CreateFcns called

% Hint: popupmenu controls usually have a white background on Windows.
%       See ISPC and COMPUTER.
if ispc && isequal(get(hObject,'BackgroundColor'), get(0,'defaultUicontrolBackgroundColor'))
    set(hObject,'BackgroundColor','white');
end

在这个示例代码中，我们使用了一个包含多个输入框和下拉框的GUI界面，并且添加了一个"Calculate"按钮来触发计算曲线积分和曲面积分的函数。你可以根据自己的需求来修改和添加GUI界面的