[Tutor] file enigma

[Tim Golden]

spir wrote:
> Hello,
> 
> text = file(filename).read()
> 
> (or: open(filename).read())
> 
> How do you close() the file? ;-)

Well, in any version of Python, you can do this:

<code>
f = open (filename)
text = f.read ()
f.close ()
</code>

or, slightly more robsustly:

<code>
f = open (filename)
try:
  text = f.read ()
finally:
  f.close ()
</code>

But in Python 2.5+ that can be spelt:

<code>
with open (filename) as f:
  text = f.read ()
</code>


As it happens, in CPython at the moment, the file object will
be closed when all references are released -- which would be
at the end of the line in your example. I don't know whether
that's guaranteed by the implementation, or merely the case
at present. It's certainly *not* the case in other implementations,
such as IronPython & Jython which don't use the same kind of
refcounting.

FWIW, in non-critical code I often use the style you illustrate
above: text = open (filename).read (). But in production code,
I usually use the with statement.


TJG