FAQ
# New Ticket Created by Father Chrysostomos
# Please include the string: [perl #75466]
# in the subject line of all future correspondence about this issue.
# <URL: http://rt.perl.org/rt3/Ticket/Display.html?id=75466 >


From overload’s docs:

o Iteration

"<>"

If not overloaded, the argument will be converted to a
filehandle
or glob (which may require a stringification). The same
overloading happens both for the read-filehandle syntax "<
$var>"
and globbing syntax "<${var}>".

It hasn’t happened with globbing syntax since File::Glob was
introduced with 5.6. Actually, it does happen in miniperl and when
perl is otherwise compiled with PERL_EXTERNAL_GLOB (how do you do
that, BTW?). It can also be triggered in 5.6 with BEGIN { ++$INC{"File/
Glob.pm"} }. The latter crashes as of 5.8, but a patch I’ve just
submitted (75464) fixes that.

Also, external glob does not respect <> overloading if the overloaded
object is returned by a tied scalar.

So, the docs are wrong most of the time. In a few corner cases they
are right.

I propose that we fix the docs and eliminate this exceptional case,
making pp_glob (aka external glob) act the same way as File::Glob.

The attached patch (if there is one) should do just this.


Use of uninitialized value $category in concatenation (.) or string
at /usr/local/bin/perlbug5.13.1 line 645.
Use of uninitialized value $severity in concatenation (.) or string
at /usr/local/bin/perlbug5.13.1 line 645.
---
Flags:
category=core
severity=low
---
Site configuration information for perl 5.13.1:

Configured by sprout at Thu May 20 09:22:52 PDT 2010.

Summary of my perl5 (revision 5 version 13 subversion 1 patch
v5.13.1-4-ge77da3b) configuration:
Snapshot of: 1404b48744cfa915e3f54775feb4e9b6c10f3b91
Platform:
osname=darwin, osvers=10.0.0, archname=darwin-thread-multi-2level
uname='darwin pint.local 10.0.0 darwin kernel version 10.0.0: fri
jul 31 22:47:34 pdt 2009; root:xnu-1456.1.25~1release_i386 i386 '
config_args='-de -Dusedevel -Duseithreads -A define:d_setregid -A
define:d_setreuid -A define:d_setrgid -A define:d_setruid'
hint=recommended, useposix=true, d_sigaction=define
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 ='-fno-common -DPERL_DARWIN -no-cpp-precomp -fno-
strict-aliasing -pipe -fstack-protector -I/usr/local/include',
optimize='-O3',
cppflags='-no-cpp-precomp -fno-common -DPERL_DARWIN -no-cpp-
precomp -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/
include'
ccversion='', gccversion='4.2.1 (Apple Inc. build 5646)',
gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
ivtype='long', ivsize=4, nvtype='double', nvsize=8,
Off_t='off_t', lseeksize=8
alignbytes=8, prototype=define
Linker and Libraries:
ld='env MACOSX_DEPLOYMENT_TARGET=10.3 cc', ldflags =' -fstack-
protector -L/usr/local/lib'
libpth=/usr/local/lib /usr/lib
libs=-ldbm -ldl -lm -lutil -lc
perllibs=-ldl -lm -lutil -lc
libc=/usr/lib/libc.dylib, so=dylib, useshrplib=false,
libperl=libperl.a
gnulibc_version=''
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=bundle, d_dlsymun=undef, ccdlflags=' '
cccdlflags=' ', lddlflags=' -bundle -undefined dynamic_lookup -L/
usr/local/lib -fstack-protector'

Locally applied patches:


---
@INC for perl 5.13.1:
/usr/local/lib/perl5/site_perl/5.13.1/darwin-thread-multi-2level
/usr/local/lib/perl5/site_perl/5.13.1
/usr/local/lib/perl5/5.13.1/darwin-thread-multi-2level
/usr/local/lib/perl5/5.13.1
/usr/local/lib/perl5/site_perl
.

---
Environment for perl 5.13.1:
DYLD_LIBRARY_PATH (unset)
HOME=/Users/sprout
LANG=en_US.UTF-8
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin:/
usr/local/bin
PERL_BADLANG (unset)
SHELL=/bin/bash

Search Discussions

  • Dave Mitchell at May 31, 2010 at 1:08 pm

    On Sun, May 30, 2010 at 02:37:15PM -0700, Father Chrysostomos wrote:
    From overload’s docs:

    o Iteration

    "<>"

    If not overloaded, the argument will be converted to a
    filehandle
    or glob (which may require a stringification). The same
    overloading happens both for the read-filehandle syntax "<
    $var>"
    and globbing syntax "<${var}>".

    It hasn’t happened with globbing syntax since File::Glob was
    introduced with 5.6. Actually, it does happen in miniperl and when
    perl is otherwise compiled with PERL_EXTERNAL_GLOB (how do you do
    that, BTW?). It can also be triggered in 5.6 with BEGIN { ++$INC{"File/
    Glob.pm"} }. The latter crashes as of 5.8, but a patch I’ve just
    submitted (75464) fixes that.

    Also, external glob does not respect <> overloading if the overloaded
    object is returned by a tied scalar.

    So, the docs are wrong most of the time. In a few corner cases they
    are right.

    I propose that we fix the docs and eliminate this exceptional case,
    making pp_glob (aka external glob) act the same way as File::Glob.
    Personally I think it should be the other way round - we should fix perl
    to match the docs. ie the behaviour of '<some_expression>' should be:

    if some_expression is a ref to an overloaded object then call
    the overload iter ('<>') function;
    else if some_expression is a simple scalar etc, call readline;
    else call glob.

    That way <> becomes a general overloadable 'iterator' operator which
    doesn't stop iterating just because the expression changes a bit.


    --
    print+qq&$}$"$/$s$,$a$d$g$s$@$.$q$,$:$.$q$^$,$@$a$~$;$.$q$m&if+map{m,^\d{0\,},,${$::{$'}}=chr($"+=$&||1)}q&10m22,42}6:17a2~2.3@3;^2dg3q/s"&=~m*\d\*.*g
  • Dave Mitchell at Jan 2, 2011 at 8:06 pm

    On Mon, May 31, 2010 at 02:08:04PM +0100, Dave Mitchell wrote:
    On Sun, May 30, 2010 at 02:37:15PM -0700, Father Chrysostomos wrote:
    From overload’s docs:

    o Iteration

    "<>"

    If not overloaded, the argument will be converted to a
    filehandle
    or glob (which may require a stringification). The same
    overloading happens both for the read-filehandle syntax "<
    $var>"
    and globbing syntax "<${var}>".

    It hasn’t happened with globbing syntax since File::Glob was
    introduced with 5.6. Actually, it does happen in miniperl and when
    perl is otherwise compiled with PERL_EXTERNAL_GLOB (how do you do
    that, BTW?). It can also be triggered in 5.6 with BEGIN { ++$INC{"File/
    Glob.pm"} }. The latter crashes as of 5.8, but a patch I’ve just
    submitted (75464) fixes that.

    Also, external glob does not respect <> overloading if the overloaded
    object is returned by a tied scalar.

    So, the docs are wrong most of the time. In a few corner cases they
    are right.

    I propose that we fix the docs and eliminate this exceptional case,
    making pp_glob (aka external glob) act the same way as File::Glob.
    Personally I think it should be the other way round - we should fix perl
    to match the docs. ie the behaviour of '<some_expression>' should be:

    if some_expression is a ref to an overloaded object then call
    the overload iter ('<>') function;
    else if some_expression is a simple scalar etc, call readline;
    else call glob.

    That way <> becomes a general overloadable 'iterator' operator which
    doesn't stop iterating just because the expression changes a bit.
    No-one commented either way, so I took an Executive Decision and made
    <expr> do overloading for all overloaded expressions, with commits

    d1bea3d84afd8d32a236c8d800e5dfc0f837570e
    bff33ce02f3be5fbb5af2c3c92e9853aaa12151e
    9426e1a55981168c83a030df9bce5e0b46586581

    --
    You live and learn (although usually you just live).

Related Discussions

Discussion Navigation
viewthread | post
Discussion Overview
groupperl5-porters @
categoriesperl
postedMay 30, '10 at 9:37p
activeJan 2, '11 at 8:06p
posts3
users2
websiteperl.org

People

Translate

site design / logo © 2022 Grokbase