[27112] in Perl-Users-Digest
Perl-Users Digest, Issue: 8986 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Thu Feb 23 06:05:49 2006
Date: Thu, 23 Feb 2006 03:05:04 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Thu, 23 Feb 2006 Volume: 10 Number: 8986
Today's topics:
Re: error-prone coding styles <january.weiner@gmail.com>
Re: Implementing a "pull" (?) interface in perl xhoster@gmail.com
Re: Reading Mac / Unix / DOS text files <tadmc@augustmail.com>
Re: Reading Mac / Unix / DOS text files <january.weiner@gmail.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Thu, 23 Feb 2006 08:59:30 +0100 (CET)
From: January Weiner <january.weiner@gmail.com>
Subject: Re: error-prone coding styles
Message-Id: <dtjq12$u24$2@sagnix.uni-muenster.de>
Samwyse <samwyse@gmail.com> wrote:
> One of the very first programs (non-Perl) that I had to maintain (as
> opposed to create) was written by a joker who decided to use O as a
> variable name. Distinguishing between
> X = 0;
> and
> X = O;
> was a source of much merriment for the rest of the staff. Fortunately
> for his nose, he was quick at ducking whenever clenched fists were in
> his vicinity.
Yeah. Lack of reasonable editors or skills at using them (how do you do
"s/\(\W\)O\(\W\)/\1BloodyStupidVariableName\2/g in Notepad?) is always
a problem.
j.
--
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Date: 23 Feb 2006 02:12:14 GMT
From: xhoster@gmail.com
Subject: Re: Implementing a "pull" (?) interface in perl
Message-Id: <20060222211446.267$9Y@newsreader.com>
Arvin Portlock <nomail@sorry.com> wrote:
> xhoster@gmail.com wrote:
>
> > The easiest way is to have the application block until a new record is
> > ready. That is just what readline aka <> does:
> >
> > $parser->init($foo);
> > while (defined (my $i=$parser->get_one()) {
> > process($i);
> > };
>
> I don't understand. You are describing exactly how I want the
> interface to act but not saying how you are doing it, i.e.,
> how exactly get_one() works. But yes, that's what I'm aiming for.
OK, now I don't understand. If you give an example of how get_all() would
work, we could discuss how to make it work like get_one() (assuming I can).
But without seeing what you are currently doing, I don't know to help you
change it!
Xho
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Date: Wed, 22 Feb 2006 22:31:33 -0600
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: Reading Mac / Unix / DOS text files
Message-Id: <slrndvqel5.bc2.tadmc@magna.augustmail.com>
January Weiner <january.weiner@gmail.com> wrote:
> A. Sinan Unur <1usa@llenroc.ude.invalid> wrote:
>
>> You should use the codes for those characters rather than the escapes.
>
> Hmmm, OK, and why?
So you will *know* what character you will get.
print "\n";
outputs different characters when perl is run on different systems.
If you use the codes, everybody on every system sees what you
want them to see.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Thu, 23 Feb 2006 08:54:07 +0100 (CET)
From: January Weiner <january.weiner@gmail.com>
Subject: Re: Reading Mac / Unix / DOS text files
Message-Id: <dtjpmv$u24$1@sagnix.uni-muenster.de>
Rick Scott <rick@shadowspar.dyndns.org> wrote:
> > Why an error? (yeah, it can lead to errors, agree, but then, of
> > course, a collegue of mine says the same about using Perl)
> Why cause a greater propensity to introduce errors than one has to?
Yeah, I guess I _could_ switch to Python, which is verrry orrrdentlich,
syntax imposes coding style, etc., etc... sorry. I use Python when
teaching. I use Perl when doing my bloody job. Seriously: Perl is
notorious for shorthands, quick dirty code snippets etc. I would not have
been programming in Perl if I was ana^W careful.
> > just some basic common sense is sufficient to say when using
> > shorthand is OK and when it is a bad idea. I do use the <IF>
> > construct in few-liners that do not read more than one file. I do
> > think it is important to define variables if you are writing a
> > larger piece of code. I do not understand the whole stir about
> > this issue.
> Since there's a way to do things that lets you do everything you can
> do with a bareword filehandle without incurring the disadvantages,
> why not make a habit of using it? As of Perl 5.6, you can do this:
> open my $FILE, '<', $filename or die "Can't open file: $!";
> Then the filehandle is stored in the lexical variable $FILE (where it
> can't be stomped on by someone else's code) instead of in the package
> variable *FILE (where it can).
Thanks for these explanation, but read what I have written above. Yeah, I
know that, I use it in larger projects. I don't care about that in the
five liners. Frankly, do you use "use strict ; use warnings ;" with
one-liners run with "perl -e"? Will you try to convince me that omitting
these is a serious danger and causes a greater propensity to introduce
errors? ...with "perl -e"? Well -- I agree. Of course it does - so what?
> > > Pick up a copy of Damian Conway's "Perl Best Practices" -- he
> > > explains why this and about a thousand other `harmless style
> > > preferences' aren't harmless, aren't stylish, and definitely
> > > aren't preferable.
> >
> > So what is the problem with whitespace? Why is while(<STDIN>) more
> > harmful than while ( <STDIN> ) ?
> Actually, I'd go with the first of these two. About whitespace in
> general -- there's not necessarily too many hard and fast rules;
> you just want to make best use of it to increase the readability of
> your code. To take an extreme example,
(snip example)
Yes, I do agree with general formatting, but I was critisized for this
particular thing -- not putting space in while(<BLAH>). By the way,
> LINE:
> foreach my $line (@lines) {
> my ($registry, $cc, $type, $start, $length, $date, $status) =
> split qr{\|}, $line;
> next LINE unless $status;
> next LINE unless ($type eq 'ipv4');
> print $start;
> }
...I would most probably write as
my @info ;
for(@lines) {
($stat, $type, $start) = split /\|/ ; # info has now: registry, cc,
# type, start, length, date, status
next unless ($info[-1] && $info[2] eq 'ipv4') ;
print $info[3] ;
}
which probably is for you
> some other godawful thing.
j.
--
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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Subject: Digest Administrivia (Last modified: 6 Apr 01)
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End of Perl-Users Digest V10 Issue 8986
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