[perl #24824] Problem with base.pm calling ->isa()
Steve Hay
# Please include the string: [perl #24824]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=24824 >
This is a bug report for perl from stev...@uk.radan.com,
generated with the help of perlbug 1.34 running under perl v5.8.2.
There is a problem importing isa() from UNIVERSAL:: when also using base.pm.
I don't understand what the problem is, but it seems to be related to the
fact that base.pm calls ->isa() itself.
Running this program:
=====
use strict;
use warnings;
BEGIN {
package Foo;
our $VERSION = '1.00';
}
use base qw(Foo);
use UNIVERSAL qw(isa);
my $hashref = {a => 1, b => 2};
if (isa($hashref, 'HASH')) {
print "It's a HASH reference\n";
}
else {
print "It's not a HASH reference\n";
}
=====
produces the error "Undefined subroutine &main::isa called at ... line 13."
Removing the "use UNIVERSAL ..." line and then calling UNIVERSAL::isa()
rather than just isa() fixes it.
Swapping around the "use base..." and "use UNIVERSAL..." lines also fixes
it!
The problem seems to be related to base.pm calling ->isa() itself. The line
use base qw(Foo);
is roughly equivalent (in this context) to
BEGIN {
our @ISA = qw(Foo) unless main->isa('Foo');
}
(That BEGIN block reproduces the error shown above.)
Changing it to just
BEGIN {
our @ISA = qw(Foo);
}
also fixes things.
---
Flags:
category=library
severity=medium
---
Site configuration information for perl v5.8.2:
Configured by steveh at Tue Nov 18 15:11:07 2003.
Summary of my perl5 (revision 5 version 8 subversion 2) configuration:
Platform:
osname=MSWin32, osvers=4.0, archname=MSWin32-x86-perlio
uname=''
config_args='undef'
hint=recommended, useposix=true, d_sigaction=undef
usethreads=undef use5005threads=undef useithreads=undef
usemultiplicity=undef
useperlio=define d_sfio=undef uselargefiles=undef usesocks=undef
use64bitint=undef use64bitall=undef uselongdouble=undef
usemymalloc=y, bincompat5005=undef
Compiler:
cc='cl', ccflags ='-nologo -Gf -W3 -MD -DNDEBUG -O1 -DWIN32
-D_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT -DPERL_DEBUGGING_MSTATS
-DUSE_PERLIO -DPERL_MSVCRT_READFIX',
optimize='-MD -DNDEBUG -O1',
cppflags='-DWIN32'
ccversion='', gccversion='', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=10
ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=4
alignbytes=8, prototype=define
Linker and Libraries:
ld='link', ldflags ='-nologo -nodefaultlib -release
-libpath:"C:\perl5\lib\CORE" -machine:x86'
libpth=C:\PROGRA~1\MICROS~2\VC98\lib
libs= oldnames.lib kernel32.lib user32.lib gdi32.lib winspool.lib
comdlg32.lib advapi32.lib shell32.lib ole32.lib oleaut32.lib
netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib version.lib
odbc32.lib odbccp32.lib msvcrt.lib
perllibs= oldnames.lib kernel32.lib user32.lib gdi32.lib
winspool.lib comdlg32.lib advapi32.lib shell32.lib ole32.lib
oleaut32.lib netapi32.lib uuid.lib wsock32.lib mpr.lib winmm.lib
version.lib odbc32.lib odbccp32.lib msvcrt.lib
libc=msvcrt.lib, so=dll, useshrplib=yes, libperl=perl58.lib
gnulibc_version='undef'
Dynamic Linking:
dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
cccdlflags=' ', lddlflags='-dll -nologo -nodefaultlib -release
-libpath:"C:\perl5\lib\CORE" -machine:x86'
Locally applied patches:
---
@INC for perl v5.8.2:
C:/perl5/lib
C:/perl5/site/lib
.
---
Environment for perl v5.8.2:
HOME (unset)
LANG (unset)
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\perl5\bin
PERL5LIB (unset)
PERL_BADLANG (unset)
SHELL (unset)
------------------------------------------------
Radan Computational Ltd.
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Rafael Garcia-Suarez
>
> There is a problem importing isa() from UNIVERSAL:: when also using base.pm.
> I don't understand what the problem is, but it seems to be related to the
> fact that base.pm calls ->isa() itself.
That's a strange problem. Here's a cut-down test case.
Uncommenting the second line fixes it.
main->isa('Foo');
#\&isa;
*isa = \&UNIVERSAL::isa;
if (isa({}, 'HASH')) { print "It's a HASH reference\n"; }