[Tutor] Trying to extract the last line of a text file

[Chris Hengge]

Very informative and creative reply! Thanks for sharing :]

On 10/19/06, Danny Yoo <dyoo at hkn.eecs.berkeley.edu> wrote:
>
>
>
> >> >> file('filename.txt').readlines()[-1]
> >>
> >> > Not to hijack the thread, but what stops you from just putting a
> >> > file.close() after your example line?
> >>
> >> Which file should file.close() close?  The problem is that we don't
> >> have a handle on the particular file we want to close off.
> >>
> > Oh wow.. I totally missed that... nevermind.. ignore that question =D
>
>
> Hi Chris,
>
> No, no, it's an interesting one.  It turns out that there IS a way to
> sorta do what you're thinking:
>
> ############################################################
> class FilePool:
>      """A small demo class to show how we might keep track of
>      files opened with us."""
>      def __init__(self):
>          self.pool = []
>
>      def open(self, filename):
>          f = open(filename)
>          self.pool.append(f)
>          return f
>
>      def closeAll(self):
>          for f in self.pool:
>              f.close()
>          self.pool = []
> fp = FilePool()
> ############################################################
>
>
> Once we have FilePool, we might say something like:
>
> ##################################################################
> print "the last line is:", fp.open('filename.txt').readlines()[-1]
> fp.closeAll()
> ##################################################################
>
>
> This is similar in spirit to the idea of "autorelease" memory pools used
> by the Objective C language.  We use some resource "manager" that does
> keep a handle on resources.  That manager then has the power and
> responsiblity to call close() at some point.  So one might imagine doing
> something like:
>
> ############################################
> create a manager
> try:
>      ... # use resources that the manager doles out
> finally:
>      use the manager to close everything down
> ############################################
>
>
> So your question may have seemed like a dumb one, but it's actually a good
> one.  *grin*
>
>
> Good luck!
>
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