使用python面向对象的编程脚本打开文件的基本麻烦

Question

I'm new to OOP and am having trouble writing and executing a basic script that will open and read a file.

I'm getting an error IOError: [Errno 2] No such file or directory: '--profile-dir' when I run this. What's wrong with this and how should I fix it?

class testing(object):

    def __init__(self, filename):
        self.filename = filename
        self.words = self.file_to_text()

    def file_to_text(self):
        with open(filename, "r") as file_opened:
            text = file_opened.read()
            words = text.split()
            return words

alice = testing("alice.txt").file_to_text()
print alice

Also, if I'd like to be able to make this executable from the command line, these tweaks should make it work, right?

import sys
...
alice = testing(sys.argv[1]).file_to_text()
print alice

line to actually input in command line to run it-----> ./testing.py alice.txt

thanks in advance guys.

Answer 1

Somewhere you have a filename = '--profile-dir' defined, that is being used in with open(filename, "r") , use with open(self.filename, "r") to use the actual attribute you have defined in the class:

filename = "foob"
class testing(object):  
    def __init__(self, filename):
        self.filename = filename
        self.words = self.file_to_text()
    def file_to_text(self):
        print(filename)
        with open(filename, "r") as file_opened:
            text = file_opened.read()
            words = text.split()
            return words 

Output:

foob
IOError: [Errno 2] No such file or directory: 'foob'

Your code will work fine using sys.argv once you make the change:

import sys

class testing(object):
    def __init__(self, filename):
        self.filename = filename
        self.words = self.file_to_text()
    def file_to_text(self):
        with open(self.filename, "r") as file_opened:
            text = file_opened.read()
            words = text.split()
            return words
alice = testing(sys.argv[1]).file_to_text()
print alice

:~$ python main.py input.txt
['testing']

If you want to use ./ put #!/usr/bin/env python at the top and chmod +x to make it executable.

You can also avoid calling read and splitting using itertools.chain:

from itertools import chain
class testing(object):
    def __init__(self, filename):
        self.filename = filename
        self.words = self.file_to_text()
    def file_to_text(self):
        with open(self.filename, "r") as file_opened:
            return list(chain.from_iterable(line.split() for line in file_opened))

Answer 2

with open(filename, "r") as file_opened:

This reads from a global variable named filename , not the one that you set in your initializer. Presumably, it has the value '--profile-dir' , so it tries to open a file with that name and throws an error when it doesn't exist. You want to replace filename with self.filename to get the field in the class instance.

Answer 3

1. The error may be because of the arguments that are passed to the script, search for --profile-dir in the run configuration settings and remove it.

2. To pass the arguments from the command line, append the code below to your script

   if __name__ == '__main__': if len(sys.argv) > 1: alice = testing(sys.argv[1]).file_to_text()

Answer 4

This code uses linecache and reads any line that you want, without really opening the file. It is fast!

import linecache

class Read_Line(object):
    def __init__(self, file_input, line):
        self.file_input = file_input
        self.line = line

    def Line_to_Text(self):
        Words = linecache.getline(self.file_input, self.line)
        Words = Words.split()
        return Words

Test = Read_Line("File.txt", 3)
print Test.Line_to_Text()