我无法让私人班级装饰员工作

Question

我正在尝试获取一个私有类装饰器，或者至少是一个与类工作相关的装饰器。我一直在尝试使用内联类，但目前在运行它时遇到以下问题：

click_ImportToDB() missing 1 required positional argument: 'self'

如果您可以查看以下内容，我已经删减了很多内容并让我知道我做错了什么，那就太好了：

class frmApplication(tk.Frame):

    # THIS IS THE PRIVATE INLINE CLASS DECORATOR THAT I AM TRYING TO BUILD.
    class _form_validation():
        def __init__(self, func):
            self.func = func
        
        def __call__(self):
            # Wrap the function up in error trapping and form validation
            try:
                # Ensure the strDBPath and config file have the same value for the database
                # Ensure the database actually exists
                # Now call the function
                self.func()
            except Exception as Ex:
                strReport=Ex.args[0]
                messagebox.showerror("Error",strReport)


    #BACK TO THE frmApplication CLASS
    def __init__(self,FormParent=tk.NONE):
        .....

    def __populateDatabaseFrame(self):
        ....

    def __populateButtonFrame(self):
        #First, add a frame
        self.__objButtonFrame=ttk.Frame(self.master,border=2,relief=tk.SUNKEN)
        self.__objButtonFrame.grid(row=1,column=0,columnspan=1,sticky=tk.N+tk.S+tk.E+tk.W,padx=10,pady=10)
        F=self.__objButtonFrame
        #Configure the columns of the frame
        F.grid_columnconfigure(0,weight=1)
        #Now add an upload to database button into the frame

        # THERE IS A CALL TO click_ImportToDB HERE !!!!!
        F.__btnImportToDB=ttk.Button(F,text="Upload to Database",command=self.click_ImportToDB)
        F.__btnImportToDB.grid(row=0,column=0,sticky=tk.E+tk.W,padx=10,pady=10)



        #Now add a button to show the data
        .....

    def __createDatabase(self):
        ...

    def __selectDatabase(self):
        ...
    
    #Public Functions.
    def click_SelectDB(self):
        ...

    def click_NewDB(self):
        ....

    @_form_validation
    def click_ImportToDB(self):
        frmTop=tk.Toplevel(self.master)
        frmTop.transient(frmTop.master)
        frmTop.focus_set()
        frmTop.grab_set()
        objFrm=vID.frmImportToDB(frmTop)
        frmTop.wait_window()
        del objFrm

非常感谢

标记

Answer 1

我不确定你是否将参数从装饰器传递给函数。

class Test():
    class _decorator(object):

        def __init__(self, arg):
            self._arg = arg
            print(self._arg)
        def __call__(self):
            print("DOING SOMETHING HERE BEFORE THE FUNC EXEC")
            retval = self._arg(self)
            print("DOING SOMETHING HERE AFTER THE FUNC EXEC")

            return retval


    @_decorator
    def test_method(self):
        print("EXECUTING FUNC")
        return "RETURN FROM TEST_METHOD"

if __name__ == '__main__':
    test = Test()
    print(test.test_method())

我试图创建此代码来复制您的疑问。

尝试，将self 传递给您的函数。

如果这不起作用。您不能尝试使用 noraml 装饰器代替类装饰器，这里是相同的示例。

from functools import wraps


class Test():

    def _decorator(f):
        @wraps(f)
        def wrapped(inst, *args, **kwargs):
            print("EXECUTING BEFORE FUNC")

            return_val = f(inst, *args, **kwargs)
            print("EXECUTING AFTER FUNC")
            return return_val
        return wrapped


    @_decorator
    def test_method(self):
        print("EXECUTING FUNC")
        return "RETURN FROM TEST_METHOD"

if __name__ == '__main__':
    test = Test()
    print(test.test_method())

希望对你有帮助。

Answer 2

感谢您的帮助。第一个建议并没有真正奏效。我已经编辑了代码以帮助解释问题所在：

class Test():

    def __init__(self):
        self.name = 'test class'

    class _decorator(object):

        def __init__(self, arg):
            self.name = '_decorator class'
            self._arg = arg
            

        def __call__(self):
            print("\n---- BEFORE FUNCTION EXECUTION ----\n")
            print('self points to: "' + self.name + '"')
            print('However I really need it to point to the test class to perform validation etc.')
            self._arg(self)
            print("\n---- AFTER FUNCTION EXECUTION ----\n")


    @_decorator
    def test_method(self):
        print('self points to: "' + self.name + '"')
        print("**** Executing test_method ****")
        

if __name__ == '__main__':
    test = Test()
    test.test_method()

输出如下：

---- BEFORE FUNCTION EXECUTION ----

self points to: "_decorator class"
However I really need it to point to the test class to perform validation etc.
self points to: "_decorator class"
**** Executing test_method ****

---- AFTER FUNCTION EXECUTION ----

我确实尝试将第二个选项调整如下：

from functools import wraps

class Test():

    def __init__(self):
        self.name = 'Test Class'

    def _decorator(f):
        @wraps(f)
        def wrapped(inst, *args, **kwargs):

            print('inst points to: '+inst.name)

            print("EXECUTING BEFORE FUNC")
            return_val = f(inst, *args, **kwargs)
            print("EXECUTING AFTER FUNC")

            return return_val

        return wrapped


    @_decorator
    def test_method(self):
        print("EXECUTING FUNC")
        return "RETURN FROM TEST_METHOD"

if __name__ == '__main__':
    test = Test()
    print(test.test_method())

输出如下：

inst points to: Test Class
EXECUTING BEFORE FUNC
EXECUTING FUNC
EXECUTING AFTER FUNC
RETURN FROM TEST_METHOD

这看起来更像我所追求的。唯一的缺点是 linter 现在报告以下问题，但它并没有阻止它工作：

Method '_decorator' should have 'self' as first argument.Python(no-self-argument)