[Python-Dev] RE: [Patches] [Patch #102915] xreadlines : readlines :: xrange : range

Tim Peters tim.one@home.com
Mon, 1 Jan 2001 14:20:53 -0500

[gvanrossum, in an SF patch comment]
> Bah.  I don't like this one bit.  More complexity for a little
> bit of extra speed.
> I'm keeping this open but expect to be closing it soon unless I
> hear a really good argument why more speed is really needed in
> this area.  Down with code bloat and creeping featurism!

Without judging "the solution" here, "the problem" is that everyone's first
attempt to use line-at-a-time file input in Perl:

    while (<F>} {
        ... $_ ...;

runs 2-5x faster then everyone's first attempt in Python:

    while 1:
        line = f.readline()
        if not line:
        ... line ...

It would be beneficial to address that *somehow*, cuz 2-5x isn't just "a
little bit"; and by the time you walk a newbie thru

    while 1:
        lines = f.readlines(hintsize)
        if not lines:
        for line in lines:
            ... line ...

they feel like maybe Perl isn't so obscure after all <wink>.

Does someone have an elegant way to address this?  I believe Jeff's shot at
elegance was the other part of the patch, using (his new) xreadlines under
the covers to speed the fileinput module.

reading-text-files-is-very-common-ly y'rs  - tim