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From: abigail@delanet.com (Abigail)
Newsgroups: comp.lang.perl.misc
Subject: Re: Why $|++ instead of $|=1 ?
Date: 08 Jul 2000 12:58:54 EDT
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Reini Urban (rurban@sbox.tu-graz.ac.at) wrote on MMDIII September
MCMXCIII in <URL:news:3967456e.12650700@news>:
~~ Abigail wrote:
~~ >$| ++ is obscure and bad. $| = 1 makes it instantly clear what the
~~ >effects are.
~~
~~ joking? both are obscure and bad.
~~
~~ use English;
~~ use constant BUFFERED => 1;
~~ use constant UNBUFFERED => 0;
~~
~~ $OUTPUT_AUTOFLUSH = BUFFERED; # this is readable.
~~ $| = 1; # this is unreadable.
$OUTPUT_AUTOFLUSH = BUFFERED; is extremely obscure as it will turn
buffering *OFF*.
Furthermore, the English forms of punctuation characters are
indistinguishable from userland characters. There's nothing that gives
away that they are special, while punctuation variables look special. And
it's a hell of a lot easier not to use punctuation variables as user
variables than to not use variables that consists of characters.
Abigail
--
perl -we '$_ = q ;4a75737420616e6f74686572205065726c204861636b65720as;;
for (s;s;s;s;s;s;s;s;s;s;s;s)
{s;(..)s?;qq qprint chr 0x$1 and \161 ssq;excess;}'
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From: rurban@sbox.tu-graz.ac.at (Reini Urban)
Newsgroups: comp.lang.perl.misc
Subject: Re: Why $|++ instead of $|=1 ?
Date: Sun, 09 Jul 2000 14:02:34 GMT
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Reini:
>> use constant BUFFERED => 1;
>> use constant UNBUFFERED => 0;
Abigail:
>$OUTPUT_AUTOFLUSH = BUFFERED; is extremely obscure as it will turn
>buffering *OFF*.
oops! but the fix would in the header only.
the sources will stay readable in contrast to various obscurity
principles discussed before.
use constant BUFFERED => 0;
use constant UNBUFFERED => 1;
>Furthermore, the English forms of punctuation characters are
>indistinguishable from userland characters. There's nothing that gives
>away that they are special, while punctuation variables look special. And
>it's a hell of a lot easier not to use punctuation variables as user
>variables than to not use variables that consists of characters.
agreed. to hell with use constant.
one uses it only with XS modules with "badly designed" API's anyway.
(say "OS-near").
--
Reini
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From: mjtg@cus.cam.ac.uk (M.J.T. Guy)
Newsgroups: comp.lang.perl.misc
Subject: Re: Why $|++ instead of $|=1 ?
Date: 13 Jul 2000 15:18:26 GMT
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Abigail <abigail@delanet.com> wrote:
>
>That's what local is for. Your subs will fail to do the right thing
>if $| happens to be -1. Or imagine that some_sub has a fatal error in
>it, which is caught by an eval{}. Your entire $| ++ and $| -- will be
>hosed.
Nope. $| is magical, and can only ever take values 0 or 1. Which
means the subroutine is nonsense for other reasons.
And that also shows that $|++ is exactly the same as $|=1, so entirely
respectable if a little eccentric.
But $|-- is a very different kettle of fish.
Mike Guy
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From: tjla@guvfybir.qlaqaf.bet (Gwyn Judd)
Newsgroups: comp.lang.perl.misc
Subject: Re: Why $|++ instead of $|=1 ?
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Date: Fri, 14 Jul 2000 01:53:39 GMT
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I was shocked! How could M.J.T. Guy <mjtg@cus.cam.ac.uk>
say such a terrible thing:
>Wyzelli <wyzelli@yahoo.com> wrote:
>>
>>As I have demonstrated previously, whilst calling $|++ repeatedly leaves
>>the state of $| 'high' (or 'unbuffered' if you wish, since any non zero
>>value = unbuffered), calling $|-- repeatedly can in certain
>>circumstances cause $| to switch between a zero and non-zero value which
>>can lead to misleading results.
>
>It's not "in certain circumstances" - it's in *all* circumstances.
>
>$| is magical and can only take values 0 or 1. An attempt to set
>any nonzero value sets it to 1.
perl -we '$| = 0; $|--;$|++; print "\$| == $|";'
$| == 1
Ergo. using $|-- and $|++ is not safe as the fact that $| is magic means
that doing these things in equal (ie. balanced) numbers does not get you
back to where you started. This is a bad thing I think. You should
always use 'local'.
--
Gwyn Judd (tjla@guvfybir.qlaqaf.bet)
My return address is rot13'ed
Schlattwhapper, n.:
The window shade that allows itself to be pulled down,
hesitates for a second, then snaps up in your face.
-- Rich Hall, "Sniglets"