Multiple members of class are updated instead of one-CodePudding

I have created class File:

@dataclass
class Match:
    length: int
    pos_A: int
    pos_B: int
    f_index: int

class File:
    __name = ""
    __pos_in_list = 0
    __statements = []
    __matches = []

    def __init__(self, name: str, pos: int, statements: [Statement]):
        self.__name = name
        self.__pos_in_list = pos
        self.__statements = statements
   
    def set_matches(self, matches: [Match]):
        self.__matches.append(matches)

After putting 3 objects of class File, so i have a list A = [File, File, File] and calling:

A[0].set_matches[Match(1,2,3,4)]

all files in list A are updated, so it looks like:

pos_in_list: 0 matches: [[Match(length=1, pos_A=2, pos_B=3, f_index=4)]]
pos_in_list: 1 matches: [[Match(length=1, pos_A=2, pos_B=3, f_index=4)]]
pos_in_list: 2 matches: [[Match(length=1, pos_A=2, pos_B=3, f_index=4)]]

,but I would like to have it like:

pos_in_list: 0 matches: [[Match(length=1, pos_A=2, pos_B=3, f_index=4)]]
pos_in_list: 1 matches: []
pos_in_list: 2 matches: []

List is filled like:

    files = []
    for i in range(len(parsed_text)):
        statements = []
        for func in parsed_text[i]:
            statements.extend(parse_text_into_tokens(func   ";"))
        f = File(filenames[i], i, statements)
        files.append(f)

Where is the problem?

CodePudding user response：

You need to move variable definition inside the init method. Defining variable outside of init means that those variables will be shared amongst all objects. Same goes for __name, __pos_in_list and __statements variables too

@dataclass
class Match:
    length: int
    pos_A: int
    pos_B: int
    f_index: int

class File:
    __name = ""
    __pos_in_list = 0
    __statements = []

    def __init__(self, name: str, pos: int, statements: [Statement]):
        self.__matches = []
        self.__name = name
        self.__pos_in_list = pos
        self.__statements = statements
   
    def set_matches(self, matches: [Match]):
        self.__matches.append(matches)

CodePudding user response：

You need to add additional check inside set_matches() method. Here you need to validate, if object, you add in the list, is already present in list or not.

You can also use set instead of list for __matches, but you need to be sure, how to compare two data classes objects