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From: Ben Morrow on 6 May 2008 12:00

Quoth Ilya Zakharevich <nospam-abuse(a)ilyaz.org>:
> [A complimentary Cc of this posting was NOT [per weedlist] sent to
> Ben Morrow
> <ben(a)morrow.me.uk>], who wrote in article
> <vrf4f5-d901.ln1(a)osiris.mauzo.dyndns.org>:
> > I would normally say 'Use lexical filehandles!' at this point;
> > unfortunately, IPC::Open3 was written before they existed and the
> > obvious way
> >
> > my $pid = open3(my $CMD_IN, my $CMD_OUT, my $CMD_ERR, @cmd)...
> >
> > doesn't work (and can't be made to since undef is already meaningful).
>
> I have no idea what you mean here.
>
> sub open3 ($$$$@) {
> $_[0] = IO::Handle->new unless defined $_[0]; # Or whatever is THE
> initializer
> ...
> }

Yeah, in general you can do that; however, for the specific case of
open3, the docs say

If CHLD_ERR is false, or the same file descriptor as CHLD_OUT, then
STDOUT and STDERR of the child are on the same filehandle.

so at least the CHLD_ERR filehandle can't be autovivified. Presumably it
is felt that this behaviour can't be changed.

Ben

--
"If a book is worth reading when you are six, * ben(a)morrow.me.uk
it is worth reading when you are sixty." [C.S.Lewis]
From: xhoster on 6 May 2008 12:07
ddunham(a)taos.com (Darren Dunham) wrote:
> Ben Morrow <ben(a)morrow.me.uk> wrote:
> > I would normally say 'Use lexical filehandles!' at this point;
> > unfortunately, IPC::Open3 was written before they existed and the
> > obvious way
> >
> > my $pid = open3(my $CMD_IN, my $CMD_OUT, my $CMD_ERR, @cmd)...
> >
> > doesn't work (and can't be made to since undef is already meaningful).
>
> What's wrong with the above?

It causes cmd's stderr to go to $CMD_OUT rather than the obviously
intended $CMD_ERR.

>
> The only issue I see is that Open3 will not autogenerate a filehandle
> for stderr (instead it will combine stdout and stderr and place them
> both on the $CMD_OUT filehandle).

And this is obviously a problem if that is not what you want to happen.

Xho

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