Syntax error on a while as loop

Question

I am trying to download a web page with python 2.7.13 and go line by line to analyze it. From memory and from searching around, I found that the following code snippet would be sufficient to go line by line:

 with s as f:
    for line in f:
        print line

The variable s is defined by a file.read() and the file is defined by urllib2 opening a specified url. Unfortunately, when I run the script, I get this syntax error:

Traceback (most recent call last):
  File "a.py", line 12, in <module>
    with s as f:
AttributeError: __exit__

I'm honestly dumbfounded of what I did wrong and it would be appreciated to gain insight about my mistake.

Which version of Python takes `as` in the condition of a `while` loop? — Ignacio Vazquez-Abrams, Sep 04 '17 at 21:11
The 'as' keyword is for import statements and exceptions. In this case, you should just be able to loop directly over the file object with your `for line in f:`, no need for a while loop. — cat, Sep 04 '17 at 21:14
Your mistake is simple: that is not valid Python, and I don't now what you think you were accomplishing. — juanpa.arrivillaga, Sep 04 '17 at 21:14
I found the example here: https://stackoverflow.com/a/8010133/4415644 — Yetoo, Sep 04 '17 at 21:17
I'm foggy today, I put while instead of with. I'll accommodate. — Yetoo, Sep 04 '17 at 21:20

OneCricketeer · Accepted Answer · 2017-09-04T21:36:01.543

2

I found that the following code snippet would be sufficient to go line by line:

It is, but for file objects as in

with open(filename) as f:
    for line in f:

The variable s is defined by a file.read()

That's a string, and can't be used in the with.

and the file is defined by urllib2 opening a specified url.

That's a file-like object, but happens to be iterable

I am trying to download a web page with python 2.7.13 and go line by line to analyze it.

No useful information can be gathered from iterating lines of a website. (at least (X)HTML, JSON, etc)

Try using BeautifulSoup or XPath

edited Sep 04 '17 at 21:36

answered Sep 04 '17 at 21:29

OneCricketeer

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Alright, I just remembered I could split the lines by "\n" and the loop through the list. Like I said, I'm very foggy today. Thanks for your help. – Yetoo Sep 04 '17 at 21:33
You can, but unless your website only contains multi line text, then parsing HTML makes more sense – OneCricketeer Sep 04 '17 at 21:37

Syntax error on a while as loop

1 Answers1