Why this is unexpected indentation in Python?

Question

#!/usr/bin/python

try:
    f = open("/home/masi/r.raw", "r+")
    aBuf = f.seek(4) 
except:
    print "Error at position : ", position

events = []
for i in range(100):
    aBuf = f.seek(4);

    try:
        if aBuf[:4] == b'\xFA\xFA\xFA\xFA':
            print("E")

    except:
    #   print "\0"

f.close()

when I commented out the print of except, I get the error

    f.close()
    ^
IndentationError: expected an indented block

I think I need to have try-except because the if-clause is false often.

Why do I get this unexpected indendation?

Your `except` expects a valid indented block. It doesn't have one. That is why it fails. You can use `pass` here. But beware of the Jabberwocky and keep in mind [`except: pass` is a bad programming practise](http://stackoverflow.com/questions/21553327/why-is-except-pass-a-bad-programming-practice). — thefourtheye, Jul 09 '15 at 13:09
because your except block has no instruction. You can use `pass` — daouzli, Jul 09 '15 at 13:09
This code has problems beyond the fact that the 2nd except block doesn't have any actual code in it. [file.seek()](https://docs.python.org/2/library/stdtypes.html#file.seek) does not have a return value, so aBuf will always be [None](https://docs.python.org/2/c-api/none.html#the-none-object). — PTBNL, Jul 09 '15 at 15:01
When you say "*I need to have try-except because the if-clause is false often*" do you think that if your `if` evaluates to `False` that the `except` block will be triggered? Because that is not the case. In that situation what you are looking for is `else`. — kylieCatt, Jul 09 '15 at 17:37

score 10 · Accepted Answer · edited May 23 '17 at 12:08

10

except is expecting one or more statements.

You could write:

try:
    if aBuf[:4] == b'\xFA\xFA\xFA\xFA':
        print("E")
except:
    pass

Warning
As stated in the comments, it is not a good practice to use except: pass.
See Why is “except: pass” a bad programming practice?.

edited May 23 '17 at 12:08

Community

1
1

answered Jul 09 '15 at 13:09

Mel

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1

Good catch, missed the empty except. – Doug Jul 09 '15 at 13:14
How would you avoid passing to except block here? – Léo Léopold Hertz 준영 Jul 09 '15 at 14:24
1

You could pass, if silent is the desired behaviour, but you should specify the type of exceptions. The problem with `except` is that [it catches everything](http://stackoverflow.com/a/21553515/4720935). – Mel Jul 09 '15 at 14:37

score 0 · Answer 2 · answered Jul 09 '15 at 13:11

0

Your code from events = [] and down needs to be inside of the first try..except block. The f.close() is out of scope.

answered Jul 09 '15 at 13:11

Doug

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It's not out of scope. That's not how scoping works in Python. And if that were the problem, he'd be getting a `NameError` instead of an `IndentationError`. – Cairnarvon Jul 09 '15 at 13:17

Why this is unexpected indentation in Python?

2 Answers2