[Moscow.pm] STDIN <> и чёрная магия

[Mons Anderson]

Хз, вроде до moscow.pm должно было дойти

The problem is not in closing fd 0

Let's look at the following sample:

# dup.pl
open my $fh, '<&=',0 or die;
print fileno STDIN, ":", scalar readline STDIN;
close STDIN;
print fileno $fh, ":", scalar readline $fh;

########
bash $ { echo 1; sleep 1; echo 2; } | perl dup.pl
0:1
0:2

(During this I've investigated, that if we do echo -ne "1\n2\n" | perl dup.pl, then <$fh> receive nothing. I think that's because of buffered read. Don't know should be this considered a bug)

Then we add the same

open my $fh, '<&=',0 or die;

to the beginning of the example and check the fileno at the end

0 == fileno $fh or die "fileno fh nonzero";

then we will see, that fileno 0 was kept, it still assigned to stdin (this could be checked additionally), but the behavior of this program still the same: we got an output of PerlIO.pm

On 09.12.2011, at 16:04, Dmitry Karasik wrote:

> On Fri, Dec 09, 2011 at 03:59:44PM +0400, Mons Anderson wrote:
>> 
>> On 09.12.2011, at 15:50, Dmitry Karasik wrote:
>> 
>>> нашел, все ясно:
>>> 
>>> 1: open( STDIN, '<', \$data ) делает 'require PerlIO::scalar' - т.е. находит этот PerlIO/scalar.pm и читает его черед fd(0). Ну
>>> читает и слава богу.
>> 
>> Фиг. В моем примере, когда мы не даем закрыть fd 0 такого не происходило-бы.
>> А все равно происходит.
> 
> в каком примере? и потом, там вполне может быть implicit close
> 
> -- 
> Sincerely,
> 	Dmitry Karasik
> 
> -- 
> Moscow.pm mailing list
> moscow-pm на pm.org | http://moscow.pm.org

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