Catch STDERR in variables via open() failed?

Tobiwan has asked for the wisdom of the Perl Monks concerning the following question:

Hello,

I've a Problem with my own CPAN-Module. One of the CPAN-Tests failed (http://www.nntp.perl.org/group/perl.cpan.testers/2007/05/msg495843.html)

The test which this error causes is line 51:

45 my $w = '';
46 is(close(STDERR), 1, 'close STDERR');
47 is(open(STDERR, ">", \$w), 1, 'reopen STDERR');
48
49
50 is($test->init( abc => 1), 0, 'init with unknown parameters');
51 is(length($w) > 0, 1, 'warnings after failed init');
[download]

The $test->init() allways warns (via Carp::carp()) so it can't be that there is no warning. I think, it's the reconnect of STDERR to catch all warnings into the lexical variable $w.

Is there a known error with this behavior in perl 5.6? Or is there an error in my catch-STDERR-code? All other CPAN-tests are passed, so I think that the code is correct.

Any wisdoms about it?

__END__
tobiwan

Comment on Catch STDERR in variables via open() failed? Download Code

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Re: Catch STDERR in variables via open() failed? by shmem (Chancellor) on May 27, 2007 at 10:18 UTC
Printing to a scalar reference was introduced in 5.8, so there's nothing wrong with that failing on 5.6. --shmem _($_=" "x(1<<5)."?\n".q·/)Oo. G°\ / /\_¯/(q / ---------------------------- \__(m.====·.(_("always off the crowd"))."· ");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}	[reply]
Re: Catch STDERR in variables via open() failed? by RMGir (Prior) on May 27, 2007 at 09:33 UTC
Did perl 5.6 even support opening a stream into a scalar like that? Off the top of my head, I _think_ that's a newer feature than 5.6... Do you wind up with a file in the current directory with a name something like "SCALAR(0x1002f0a0)"? close(STDERR) followed by that same open into a variable does work under 5.8.7, if that helps... Mike	[reply]
Re: Catch STDERR in variables via open() failed? by jettero (Monsignor) on May 27, 2007 at 11:58 UTC
I love the cpan testers. I have fixed so many problems with my modules because of that project. However, getting reports that certain 5.8 things don't work in 5.6 is less helpful... I considered that my problem though. When I asked, it was because I needed a way to instruct 5.6 testers to skip a module: testers.cpan vs perl 5.8. The answer was to "use 5.008" at the top of the Makefile.PL. Although, the obvious work around was to use a code block thingy in my print statement (ie `{$fh}`). -Paul	[reply] [d/l]