On Thu, Apr 22, 2010 at 11:28 AM, J <dreadpiratej...@gmail.com> wrote:
> I was reading something from a code review a little while ago and saw
> something that's got my curiosity up...
>
> Say I had a file, foo.txt that I wanted to read from, only one time
> and only read.
>
> So what's the difference between this:
>
> mylist = Popen(["cat","foo.txt"], stdout=PIPE).communicate()[0].splitlines()
>
> and this:
>
> f = open('foo.txt')
> mylist = f.readlines()
> f.close
>
> Is there a reason why you would not use subprocess.Popen for this,
> other than just not relying on external programs to perfrom the task?
>
> what if that file only has one line in it, and that's all you're
> interested in, and the file is guaranteed to only have that one line
> it it?
>
> For example:
>
> say foo.txt contained only the number 123456789
>
> what's wrong with doing this:
>
> my_int = int(commands.getoutput('cat foo.txt')
>
> or via the subprocess.Popen method mentioned above?- Unnecessary complexity; I don't think anyone can credibly argue the versions that use cat are simpler than the just-read-the-file-directly version - Unnecessary dependency (Does Windows have cat? I honestly don't know.) - Pointless waste of CPU time; the versions invoking cat are slower and there is no corresponding reward for enduring the decrease in performance - Bad error reporting; if foo.txt is nonexistent, the cat-free version will give you a nice juicy IOError with full traceback, whereas the cat versions will just silently give you an empty string In other words, why *would* you want to use cat for this? The versions using it have absolutely no benefits that I can find over the cat-free code. Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
