Opening files without closing them

[Bruno Desthuilliers]

Sandra-24 a écrit :
> I was reading over some python code recently, and I saw something like
> this:
> 
> contents = open(file).read()
> 
> And of course you can also do:
> 
> open(file, "w").write(obj)
> 
> Why do they no close the files? Is this sloppy programming or is the
> file automatically closed when the reference is destroyed (after this
> line)? 

IIRC, the current CPython implementation takes care of closing file 
objects that are no longer referenced. But this may not be true of other 
implementations (think: Jython).

> I usually use:
> 
> try:
>   f = open(file)
>   contents = f.read()
> finally:
>   f.close()
> 
> But now I am wondering if that is the same thing. 

Not quite:

 >>> try:
...     f = open('file_that_doesnt_exists.ext')
... finally:
...     f.close()
...
Traceback (most recent call last):
   File "<stdin>", line 4, in ?
NameError: name 'f' is not defined
 >>>

> Which method would
> you rather use? 

For a quick script, the simplest one. For production code, it depends 
too much on the context to give a definitive single answer.