Python类中未定义OOP变量需要帮助理解\uuu init__

Question

我是OOP新手，我一直在尝试编写一个可以导入的类，它将帮助我解析文件。我意识到我不需要制作一个类来做这件事，但我想我会尝试这样做，这样我就可以开始熟悉OOP了

此代码有效

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)

这段代码没有，我不知道为什么没有

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)

我收到错误消息： 第10行，在GetNums中 使用open（os.path.join（destdir，source），'r'）作为内嵌： NameError:未定义名称“destdir”

我的理解是，类对象的名称空间将允许类中的函数查看该类中声明的所有变量

Answer 1

您需要将第10行更改为：

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

在您的例子中，Python首先在GetNums中查找testdir，如果在那里找不到，它将在模块中查找该名称。它不会神奇地使用来自__init__的tesdir。名称self代表稍后创建的实例。因此，在__init__中，您基本上设置了mysinstance.testdir，稍后在GetNums中，您可以使用mysinstance.testdir进行访问self只是mysinstance的占位符，即稍后创建的实例

您可以在documentation中阅读详细信息

Answer 2

@Mike Müller搞定了，但下面是完整的更正代码

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)