python类中的全局变量赋值

Question

My XmlParser receive file name and then read by filename and then create my soup for different methods. I try to make soup global variable. But I refer to constructor variable and i response: 'NameError: name 'self' is not defined'

from bs4 import BeautifulSoup
from tools import read_file


class XmlParser:
    soup = BeautifulSoup(self.xml_file, self.parser_type)

    def __init__(self, file_name, parser_type):
        self.xml_file = read_file(file_name)
        self.parser_type = parser_type

How can i create my soup variable before constructor assignment?

Answer 1

My XmlParser receive file name and then read by filename and then create my soup for different methods.

In that case the BeautifulSoup instance should be the only class variable. In your methods you then can refer to it as self.soup . There is no need to expose file_name and parser_type to any other methods due to they are only specific to the BeautifulSoup instantiation which happens inside of the constructor __init__ .

from bs4 import BeautifulSoup
from tools import read_file

class XmlParser:    
  def __init__(self, file_name, parser_type):
    xml_file = read_file(file_name)
    self.soup = BeautifulSoup(xml_file, parser_type)

  def method_1(self):
    # access self.soup here

  def method_2(self):
    # access self.soup here