Python類中未定義的OOP變量-需要幫助了解__init__

Question

我是OOP的新手，我一直在嘗試編寫一個可以導入的類，這將有助於我解析文件。 我意識到我不需要上一堂課來做，但是我想我會盡力讓我開始熟悉OOP。

此代碼有效

import re
import os

destdir = r"FilePathToDirectory"

class Parsey():                            

    def GetNums(self,source, destination, trim = True):
        with open (os.path.join(destdir,source), 'r') as infile:
            with open (os.path.join(destdir,destination), 'w') as outfile:
                for line in infile:
                    #Look for number patern match
                    if re.match(r'(.*)\d\d-\d\d-\d\d\d\d(.*)', line):
                        #If trim is True clean up the line
                        if trim == True:
                            #Find the first numeric character
                            firstdig = re.search("\d",line)
                            #Set the firstdig variable to the integer of that index
                            firstdig = firstdig.start()
                            #Set the line equal to only the begining and ending indexes of the number
                            line=line[firstdig:firstdig+10]
                            #Remove the dashes from the string
                            line = line.replace('-','')
                            outfile.writelines(line+'\n')
                        else:
                            outfile.writelines(line)

這段代碼沒有，我不確定為什么不這樣做。

import re
import os

class Parsey():

    def __init__(self, destdir=''):
        self.destdir = r"FilePathToDirectory"

    def GetNums(self,source, destination, trim = True):
        with open (os.path.join(destdir,source), 'r') as infile:
            with open (os.path.join(destdir,destination), 'w') as outfile:
                for line in infile:
                    #Look for number patern match
                    if re.match(r'(.*)\d\d-\d\d-\d\d\d\d(.*)', line):
                        #If trim is True clean up the line
                        if trim == True:
                            #Find the first numeric character
                            firstdig = re.search("\d",line)
                            #Set the firstdig variable to the integer of that index
                            firstdig = firstdig.start()
                            #Set the line equal to only the begining and ending indexes of the number
                            line=line[firstdig:firstdig+11]
                            #Remove the dashes from the string
                            line = line.replace('-','')
                            outfile.writelines(line+'\n')
                        else:
                            outfile.writelines(line)

我收到錯誤：第10行，在GetNums中，以infile格式打開（os.path.join（destdir，source），'r'）：NameError：未定義名稱'destdir'

據我了解，類對象的名稱空間將允許類中的函數查看該類中聲明的所有變量。

Answer 1

您需要將第10行更改為：

with open (os.path.join(self.destdir, destination), 'w') as outfile:

在您的情況下，Python首先在GetNums查找testdir ，如果無法在其中找到它，它將在模塊中查找該名稱。 它不會神奇地使用__init__ tesdir 。 名稱self代表您以后創建的實例。 因此，在__init__您基本上設置了mysinstance.testdir ，以后在GetNums可以使用mysinstance.testdir進行訪問。 self只是mysinstance的占位符，即您以后創建的實例。

您可以在文檔中閱讀詳細信息 。

Answer 2

@MikeMüller釘牢了它，但這是完整的更正代碼。

import re
import os

class Parsey():

    def __init__(self, destdir=''):
        self.destdir = r"FilePathToDirectory"

    def GetNums(self,source, destination, trim = True):
        with open (os.path.join(self.destdir,source), 'r') as infile:
            with open (os.path.join(self.destdir,destination), 'w') as outfile:
                for line in infile:
                    #Look for number patern match
                    if re.match(r'(.*)\d\d-\d\d-\d\d\d\d(.*)', line):
                        #If trim is True clean up the line
                        if trim == True:
                            #Find the first numeric character
                            firstdig = re.search("\d",line)
                            #Set the firstdig variable to the integer of that index
                            firstdig = firstdig.start()
                            #Set the line equal to only the begining and ending indexes of the number
                            line=line[firstdig:firstdig+10]
                            #Remove the dashes from the string
                            line = line.replace('-','')
                            outfile.writelines(line+'\n')
                        else:
                            outfile.writelines(line)