[perl #37128] undefing *foo{CODE} does not fully work

2005-09-10 Thread via RT 
# New Ticket Created by  Ben Tilly 
# Please include the string:  [perl #37128]
# in the subject line of all future correspondence about this issue. 
# URL: https://rt.perl.org/rt3/Ticket/Display.html?id=37128 



This is a bug report for perl from [EMAIL PROTECTED],
generated with the help of perlbug 1.34 running under perl v5.8.3.


-
[Please enter your report here]

This problem has been seen on Perl 5.8.3 and 5.8.7.  I assume that
it happens under other versions as well.

If you try to undef the CODE slot of a glob, it only halfway works.
ref(*foo{CODE}) will still show that it is a code reference, and
UNIVERSAL::can still shows that it is a code reference.

This bug causes problems when Apache::Reload and Class::DBI are
used together.

The following code sample demonstrates what I am talking about


#! /usr/bin/perl -l
print Originally foo() is a  . ref(*foo{CODE});
print Initializing foo();
*foo = sub {print hello};
print foo() is now a  . ref(*foo{CODE});
print According to can, foo is  . main-can(foo);
print Calling foo();
foo();

print Undefining foo();
$x = *foo;
undef $x;
print foo() is now a  . ref(*foo{CODE});
print According to can, foo is  . main-can(foo);
print Calling foo();
foo();

__END__
Originally foo() is a 
Initializing foo()
foo() is now a CODE
According to can, foo is CODE(0x8175b24)
Calling foo()
hello
Undefining foo()
foo() is now a CODE
According to can, foo is CODE(0x8175b24)
Calling foo()


The way that this comes into play in the case that I mention is
that Apache::Reload attempts to undefine subroutines that have
been defined, but when Class::DBI tries to check whether they
are there it is told that they are, with disasterous results.

[Please do not change anything below this line]
-
---
Flags:
category=core
severity=medium
---
Site configuration information for perl v5.8.3:

Configured by Debian Project at Sun Feb 15 17:22:09 EST 2004.

Summary of my perl5 (revision 5.0 version 8 subversion 3) configuration:
  Platform:
osname=linux, osvers=2.4.22-xfs+ti1211, archname=i386-linux-thread-multi
uname='linux kosh 2.4.22-xfs+ti1211 #1 sat oct 25 10:11:37 est 2003 i686 
gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN 
-Dcccdlflags=-fPIC -Darchname=i386-linux -Dprefix=/usr 
-Dprivlib=/usr/share/perl/5.8 -Darchlib=/usr/lib/perl/5.8 -Dvendorprefix=/usr 
-Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 
-Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.8.3 
-Dsitearch=/usr/local/lib/perl/5.8.3 -Dman1dir=/usr/share/man/man1 
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 
-Dsiteman3dir=/usr/local/man/man3 -Dman1ext=1 -Dman3ext=3perl 
-Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib 
-Dlibperl=libperl.so.5.8.3 -Dd_dosuid -des'
hint=recommended, useposix=true, d_sigaction=define
usethreads=define use5005threads=undef useithreads=define 
usemultiplicity=define
useperlio=define d_sfio=undef uselargefiles=define usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=n, bincompat5005=undef
  Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN 
-fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE 
-D_FILE_OFFSET_BITS=64',
optimize='-O3',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DTHREADS_HAVE_PIDS -DDEBIAN 
-fno-strict-aliasing -I/usr/local/include'
ccversion='', gccversion='3.3.3 20040125 (prerelease) (Debian)', 
gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t', 
lseeksize=8
alignbytes=4, prototype=define
  Linker and Libraries:
ld='cc', ldflags =' -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=/lib/libc-2.3.2.so, so=so, useshrplib=true, libperl=libperl.so.5.8.3
gnulibc_version='2.3.2'
  Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-rdynamic'
cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib'

Locally applied patches:


---
@INC for perl v5.8.3:
/etc/perl
/usr/local/lib/perl/5.8.3
/usr/local/share/perl/5.8.3
/usr/lib/perl5
/usr/share/perl5
/usr/lib/perl/5.8
/usr/share/perl/5.8
/usr/local/lib/site_perl
/usr/local/lib/perl/5.8.2
/usr/local/share/perl/5.8.2
/usr/local/lib/perl/5.8.1
/usr/local/share/perl/5.8.1
/usr/local/lib/perl/5.8.0
/usr/local/share/perl/5.8.0
.

---
Environment for perl v5.8.3:
HOME=/home/btilly
LANG (unset)
LANGUAGE (unset)
LD_LIBRARY_PATH=/usr/local/oracle/lib
LOGDIR (unset)

Re: [perl #37128] undefing *foo{CODE} does not fully work

2005-09-10 Thread Dave Mitchell 
On Fri, Sep 09, 2005 at 06:11:49PM -0700, Ben Tilly wrote:
 If you try to undef the CODE slot of a glob, it only halfway works.
 ref(*foo{CODE}) will still show that it is a code reference, and
 UNIVERSAL::can still shows that it is a code reference.

Undefing a sub is not the same as deleting a sub. Internally, the CV
continues to exist, but its pad and op tree are freed. cf:

$ perl587 -le 'my $x = []; undef @$x; print $x'
ARRAY(0x9c7d180)
$ perl587 -le 'my $x = sub {}; undef $x; print $x'
CODE(0x8e40bac)

In both cases the thing continues to exist, but has no useful 'value'.

-- 
My get-up-and-go just got up and went.

re: [perl #37128] undefing *foo{CODE} does not fully work

2005-09-10 Thread Ben Tilly 
When I looked at the way the message appeared on the list, I realized
that I forgot to include one line of output.  The one where it dies. 
Here is the program and output with that additional piece of
information.

And to clarify the Class::DBI/Apache::Reload conflict that this
causes, load up the page and look at it.  You see a web page.  Make a
trivial modification to the underlying code.  You get internal server
errors because it can't figure out that there aren't really accessors
there for it to go and call.

Cheers,
Ben

#! /usr/bin/perl -l
print Originally foo() is a  . ref(*foo{CODE});
print Initializing foo();
*foo = sub {print hello};
print foo() is now a  . ref(*foo{CODE});
print According to can, foo is  . main-can(foo);
print Calling foo();
foo();

print Undefining foo();
$x = *foo;
undef $x;
print foo() is now a  . ref(*foo{CODE});
print According to can, foo is  . main-can(foo);
print Calling foo();
foo();

__END__
Originally foo() is a
Initializing foo()
foo() is now a CODE
According to can, foo is CODE(0x8158f10)
Calling foo()
hello
Undefining foo()
foo() is now a CODE
According to can, foo is CODE(0x8158f10)
Calling foo()
Not a CODE reference at - line 16.

Re: [perl #37128] undefing *foo{CODE} does not fully work

2005-09-10 Thread Rafael Garcia-Suarez 
On 9/10/05, Dave Mitchell [EMAIL PROTECTED] wrote:
 Undefing a sub is not the same as deleting a sub. Internally, the CV
 continues to exist, but its pad and op tree are freed. cf:

One of the items on the todo list is to allow the construct

delete foo;

I could finish my patch to do it if I could figure out how to delete a
CV cleanly from all the stashes where it's referenced... (subs have
this tendency to be exported in other stashes.)