Re^4: Track open file handles

This prevents the call to the standard open to autovivify a GLOB when none is available.

It shouldn't be prevented. If it autovivifies, I want to know about that. This Blorfldyick is meant to be transparent, while adding overhead and slowing things down... ;-)

It's not easy, open is a complex beast. I'm reaching into the pile of rhinos... open can be provided a lexical var, a package var (populated or not), a typeglob, a bareword, a Symbol (via gensym) and what not, as the first argument. Trying to wrap my head around all that... thanks for your input, Eily++

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

Comment on Re^4: Track open file handles

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Re^5: Track open file handles by salva (Canon) on Apr 07, 2017 at 08:57 UTC
In order to avoid the wrong caller package issue, you can create a wrapping sub for `open` in the caller package and jump there using `goto &$sub` which overwrites the current stack frame. Something similar to the following code: `package MyOpen; use Carp (); use Data::Dumper; use 5.010; my %cache; BEGIN { *CORE::GLOBAL::open = sub { my $pkg = caller; my $sub = $cache{$pkg} //= do { my $code = <<EOS; package $pkg; sub { my \$r = CORE::open \$_[0], \@_[1..\$#_]; Carp::cluck(Data::Dumper::Dumper(\@_)); return \$r; } EOS eval $code or die "Bad sub: $@"; }; goto &$sub; }; } package main; open $fh, '>&', 'STDOUT'; open FOO, ">", "/tmp/FOO";` [download]	[reply] [d/l] [select]
Re^6: Track open file handles by shmem (Chancellor) on Apr 07, 2017 at 09:36 UTC
Thank you. I was thinking about taking this road, using eval to switch package. I can't `goto &$sub` to erase the current stack frame, because I need to do the track housekeeping after the open, and record the (possible mutated) `$_[0]`. OTOH... thinking about it, I could switch package in that eval'ed sub again and do the housekeeping there. To that end, the `%fh` fieldhash must be a package var. Oh well. Currently, I am inspecting `$_[0]` with Devel::Caller etc. to find out whether the filehandle variable is lexical, package global, typeglob, bareword etc and trying to do the right thing. Anyways the overridden `open` would show up in the stack trace of `Carp::cluck`, so another stack frame wouldn't matter I guess. But with Sub::Name I could make that sub into the calling package. Maybe that's the best way to do it. It is definitely the cheapest in effort :-) update: and maybe the most robust also... Thanks again, salva! perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'	[reply] [d/l] [select]


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