i have a problem with using __getattribute__

I have a school task that i need to do. I should create an object when constructor where when you put a list as an argument it only takes the string from the list and put them in the attribute of the class. When you try to print the list, it should only print the first characters of each string in the list. For example, if i put [1,2,3,4,"something","word"] the attribute should contain ["something","word"] and when you print it on the console it should pop up sw. I must use __getattribute__.

This is the code that I wrote

class Myclass:

    def __init__(self, L):
        self.lst = []
        self.txt = ""

        if type(L) == list:
            for i in range(len(L)):
                if type(L[i]) == str:
                    self.lst.append(L[i])

            for i in range(len(self.lst)):
                self.txt += self.lst[i][0]

    def __getattribute__(self, name):
        if name == "lst":
            return object.__getattribute__(self, "txt")
        else:
            return object.__getattribute__(self, name)


objA = Myclass([1, 2, 3, 4, 5, "something", "word"])
print(objA.lst)
print(objA.txt)

it gives me AttribureError:

  File "c:\Users\User\Desktop\python\book2\unit2\project6.py", line 25, in <module>
    objA = Myclass([1, 2, 3, 4, 5, "something", "word"])
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "c:\Users\User\Desktop\python\book2\unit2\project6.py", line 13, in __init__
    self.lst.append(L[i])
    ^^^^^^^^^^^^^^^
AttributeError: 'str' object has no attribute 'append

I made attribute private. __getattribute__ method is used in both cases: creating object and accessing by print(objA.lst).

In the case of creating object, self._lst.append(item) calls __getattribute__ under the hood. Like self.__getattribute__('_lst')

class Myclass:

    def __init__(self, L):
        self._lst = []  # private attribute to hold the list of strings
        self.txt = ""

        if isinstance(L, list):
            for item in L:
                if isinstance(item, str):
                    self._lst.append(item)
                    self.txt += item[0]

    def __getattribute__(self, name):
        if name == "lst":
            return object.__getattribute__(self, "txt")
        else:
            return object.__getattribute__(self, name)


if __name__ == '__main__':
    objA = Myclass([1, 2, 3, 4, 5, "something", "word"])
    print(objA.lst)  # prints 'sw'

There is no need to use range on lists, just enumerate the list. As follows:

class Myclass():

def __init__(self, L):
    self.txt = ""

    if type(L) == list:
        for s in L:
            if type(s) == str:
                self.txt += s[0:1]

def __getattribute__(self, name):
    if name == "lst":
        return object.__getattribute__(self, "txt")
    else:
        return object.__getattribute__(self, name)


objA = Myclass([1, 2, 3, 4, 5, "something", "word", ""])
print(objA.lst)
print(objA.txt)

I believe you have solved this in reverse. You do not need to construct the "txt" attribute, because that's exactly how lists print themselves. Consider:

class Myclass:

    def __init__(self, L):
        self.lst = []

        if type(L) == list:
            for i in L:
                if type(i) == str:
                    self.lst.append(i)

    def __getattribute__(self, name):
        if name == "txt":
            lst =  object.__getattribute__(self, "lst")
            return ''.join(l[0] for l in lst)
        else:
            return object.__getattribute__(self, name)


objA = Myclass([1, 2, 3, 4, 5, "something", "word"])
print(objA.lst)
print(objA.txt)

Output:

['something', 'word']
sw

Note that your design doesn't work if you add to lst later, whereas this design will.

In my opinion most elegant and readable way to accomplish that is by overriding collections UserList init and all methods that takes care of adding elements + the one for getting list to only return first letters.