Using each @array as while iterator exits on first (0th) index

[p5pRT]

Migrated from rt.perl.org#90888 (status was 'resolved')

Searchable as RT90888$

[p5pRT]

From joel.a.berger@gmail.com

Created by joel.a.berger@gmail.com

The new functionality which allows `each` to be called on an array lacks one
useful design element. When called as `while (my $i = each @​array) { ... }` the
loop exits on the first iteration since the first index is 0. A brief discussion
can be found at http​://stackoverflow.com/q/6033750/468327 . In it another poster
mentions that "`perl -MO=Deparse -E'...'` tells me that `while (my $i
= each %h)` is
deparsed as `while(defined(my $i = each %h))`, but the same isn't true
for arrays."
I think the principal of least confusion would state that using
`while(each @​array)`
should not die for the 0th element.

Thanks for this new feature, I have been eagerly awaiting being able
to iterate over
the indices of an array. One more change and it will be perfect!

Perl Info

Flags:
    category=core
    severity=low

Site configuration information for perl 5.14.0:

Configured by joel at Sun Apr 24 19:51:41 CDT 2011.

Summary of my perl5 (revision 5 version 14 subversion 0) configuration:

  Platform:
    osname=linux, osvers=2.6.35-28-generic, archname=x86_64-linux
    uname='linux joel-ubuntu 2.6.35-28-generic #50-ubuntu smp fri mar
18 18:42:20 utc 2011 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/joel/perl5/perlbrew/perls/perl-5.14.0-RC1'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector
-I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
    ccversion='', gccversion='4.4.5', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/../lib /usr/lib/../lib /lib /usr/lib
/usr/lib/x86_64-linux-gnu /lib64 /usr/lib64
    libs=-lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
    perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
    libc=/lib/libc-2.12.1.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.12.1'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib
-fstack-protector'

Locally applied patches:
    RC1


@INC for perl 5.14.0:
    /home/joel/Programs/Perl5Lib
    /home/joel/perl5/perlbrew/perls/perl-5.14.0-RC1/lib/site_perl/5.14.0/x86_64-linux
    /home/joel/perl5/perlbrew/perls/perl-5.14.0-RC1/lib/site_perl/5.14.0
    /home/joel/perl5/perlbrew/perls/perl-5.14.0-RC1/lib/5.14.0/x86_64-linux
    /home/joel/perl5/perlbrew/perls/perl-5.14.0-RC1/lib/5.14.0
    .


Environment for perl 5.14.0:
    HOME=/home/joel
    LANG=en_US.utf8
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/joel/perl5/perlbrew/bin:/home/joel/perl5/perlbrew/perls/current/bin:/home/joel/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/joel/Programs/Perl5Lib
    PERL5LIB=/home/joel/Programs/Perl5Lib
    PERLBREW_PATH=/home/joel/perl5/perlbrew/bin:/home/joel/perl5/perlbrew/perls/current/bin
    PERLBREW_PERL=perl-5.14.0-RC1
    PERLBREW_ROOT=/home/joel/perl5/perlbrew
    PERLBREW_VERSION=0.18
    PERL_BADLANG (unset)
    SHELL=/bin/bash

[p5pRT]

From am0c@perl.kr

commit 329521539b6f17f285367182890c6b24a7fdf408
Author​: Hojung Yoon <amoc.yn@​gmail.com>
Date​:   Wed May 25 03​:41​:53 2011 +0900

   [perl #90888] each(ARRAY) on scalar context should wrapped into defined()

   "perldoc -f each" says that if each() is performed on ARRAY
   in scalar context, it will return only the index in an array.
   Calling each(HASH) in scalar context worked well but calling
   each(ARRAY) didn't because it was not wrapped into defined OPCODE.

   So, in Perl_newWHILEOP() and Perl_newLOOPOP(), they are modified
   to check them and wrap with defined OP if needed.

   In S_new_logop(), it's reasonable to warn if return value of
   each(ARRAY) is being used for boolean value, as it's first return
   value will be "0", the false.

   issue​: #90888
   link​: http​://rt.perl.org/rt3/Public/Bug/Display.html?id=90888

commit ceb12f1
Author​: Johan Vromans <jvromans@​squirrel.nl>
Date​:   Tue May 24 08​:35​:37 2011 -0700

   [perl #91518] Fix minor typo in pod/perlsub.pod.

---

From 329521539b6f17f285367182890c6b24a7fdf408 Mon Sep 17 00​:00​:00 2001
From​: Hojung Yoon <amoc.yn@​gmail.com>
Date​: Wed, 25 May 2011 03​:41​:53 +0900
Subject​: [PATCH] [perl #90888] each(ARRAY) on scalar context should
wrapped into defined()

"perldoc -f each" says that if each() is performed on ARRAY
in scalar context, it will return only the index in an array.
Calling each(HASH) in scalar context worked well but calling
each(ARRAY) didn't because it was not wrapped into defined OPCODE.

So, in Perl_newWHILEOP() and Perl_newLOOPOP(), they are modified
to check them and wrap with defined OP if needed.

In S_new_logop(), it's reasonable to warn if return value of
each(ARRAY) is being used for boolean value, as it's first return
value will be "0", the false.

issue​: #90888
link​: http​://rt.perl.org/rt3/Public/Bug/Display.html?id=90888

---

 op.c              |    9 ++++++---
 t/op/each_array.t |   45 +++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 5 deletions(-)

Inline Patch

diff --git a/op.c b/op.c
index 0d4e1e6..8d333e9 100644
--- a/op.c
+++ b/op.c
@@ -5103,7 +5103,8 @@ S_new_logop(pTHX_ I32 type, I32 flags, OP**

firstp, OP** otherp)            if \(k1\->op\_type == OP\_READDIR                  || k1\->op\_type == OP\_GLOB                  || \(k1\->op\_type == OP\_NULL && k1\->op\_targ == OP\_GLOB\) \-                 || k1\->op\_type == OP\_EACH\) \+                 || k1\->op\_type == OP\_EACH \+                 || k1\->op\_type == OP\_AEACH\)            \{                warnop = \(\(k1\->op\_type == OP\_NULL\)                          ? \(OPCODE\)k1\->op\_targ : k1\->op\_type\); @​@​ \-5347\,7 \+5348\,8 @​@​ Perl\_newLOOPOP\(pTHX\_ I32 flags\, I32 debuggable\, OP \*expr\, OP \*block\)                if \(k1 && \(k1\->op\_type == OP\_READDIR                      || k1\->op\_type == OP\_GLOB                      || \(k1\->op\_type == OP\_NULL && k1\->op\_targ == OP\_GLOB\) \-                     || k1\->op\_type == OP\_EACH\)\) \+                     || k1\->op\_type == OP\_EACH \+                     || k1\->op\_type == OP\_AEACH\)\)                    expr = newUNOP\(OP\_DEFINED\, 0\, expr\);                break;            \} @​@​ \-5435\,7 \+5437\,8 @​@​ Perl\_newWHILEOP\(pTHX\_ I32 flags\, I32 debuggable\, LOOP \*loop\,                if \(k1 && \(k1\->op\_type == OP\_READDIR                      || k1\->op\_type == OP\_GLOB                      || \(k1\->op\_type == OP\_NULL && k1\->op\_targ == OP\_GLOB\) \-                     || k1\->op\_type == OP\_EACH\)\) \+                     || k1\->op\_type == OP\_EACH \+                     || k1\->op\_type == OP\_AEACH\)\)                    expr = newUNOP\(OP\_DEFINED\, 0\, expr\);                break;            \}

Inline Patch

diff --git a/t/op/each_array.t b/t/op/each_array.t
index 2389473..9a6073a 100644
--- a/t/op/each_array.t
+++ b/t/op/each_array.t
@@ -8,9 +8,9 @@ BEGIN {
 use strict;
 use warnings;
 no warnings 'deprecated';
-use vars qw(@array @r $k $v);
+use vars qw(@array @r $k $v $c);

-plan tests => 48;
+plan tests => 66;

 @array = qw(crunch zam bloop);

@@ -132,3 +132,44 @@ is ("@values", "@array");
 ($k, $v) = each @array;
 is ($k, 0);
 is ($v, 'crunch');
+
+# reset
+$[ = 0;
+while (each @array) { }
+
+# each(ARRAY) in the conditional loop
+$c = 0;
+while (($k, $v) = each @array) {
+    is ($k, $c);
+    is ($v, $array[$k]);
+    $c++;
+}
+
+# each(ARRAY) on scalar context in conditional loop
+# should guarantee to be wrapped into defined() function.
+# first return value will be $[ --> [#90888]
+$c = 0;
+$k = 0;
+$v = 0;
+while ($k = each @array) {
+    is ($k, $v);
+    $v++;
+}
+
+# each(ARRAY) in the conditional loop
+$c = 0;
+for (; ($k, $v) = each @array ;) {
+    is ($k, $c);
+    is ($v, $array[$k]);
+    $c++;
+}
+
+# each(ARRAY) on scalar context in conditional loop
+# --> [#90888]
+$c = 0;
+$k = 0;
+$v = 0;
+for (; $k = each(@array) ;) {
+    is ($k, $v);
+    $v++;
+}
--

1.7.0.4

---

---

Flags​:
   category=core
   severity=medium

---

Site configuration information for perl 5.14.0​:

Configured by am0c at Mon May 23 09​:46​:57 KST 2011.

Summary of my perl5 (revision 5 version 14 subversion 0) configuration​:

 Platform​:
   osname=linux, osvers=2.6.32-31-generic, archname=i686-linux-thread-multi
   uname='linux amolap 2.6.32-31-generic #61-ubuntu smp fri apr 8
18​:24​:35 utc 2011 i686 gnulinux '
   config_args='-de
-Dprefix=/home/am0c/perl5/perlbrew/perls/perl-5.14.0 -Dusethreads'
   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 ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
   optimize='-O2',
   cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe
-fstack-protector -I/usr/local/include'
   ccversion='', gccversion='4.4.3', 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 =' -fstack-protector -L/usr/local/lib'
   libpth=/usr/local/lib /lib/../lib /usr/lib/../lib /lib /usr/lib
/usr/lib/i486-linux-gnu /usr/lib64
   libs=-lnsl -ldb -ldl -lm -lcrypt -lutil -lpthread -lc
   perllibs=-lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
   libc=/lib/libc-2.11.1.so, so=so, useshrplib=false, libperl=libperl.a
   gnulibc_version='2.11.1'
 Dynamic Linking​:
   dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
   cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib
-fstack-protector'

Locally applied patches​:

---

@​INC for perl 5.14.0​:
   /home/am0c/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0/i686-linux-thread-multi
   /home/am0c/perl5/perlbrew/perls/perl-5.14.0/lib/site_perl/5.14.0
   /home/am0c/perl5/perlbrew/perls/perl-5.14.0/lib/5.14.0/i686-linux-thread-multi
   /home/am0c/perl5/perlbrew/perls/perl-5.14.0/lib/5.14.0
   .

---

Environment for perl 5.14.0​:
   HOME=/home/am0c
   LANG=en_US.utf8
   LANGUAGE (unset)
   LD_LIBRARY_PATH (unset)
   LOGDIR (unset)
   PATH=/home/am0c/.rvm/gems/ruby-1.9.2-p0/bin​:/home/am0c/.rvm/gems/ruby-1.9.2-p0@​global/bin​:/home/am0c/.rvm/rubies/ruby-1.9.2-p0/bin​:/home/am0c/.rvm/bin​:/home/am0c/perl5/perlbrew/bin​:/home/am0c/perl5/perlbrew/perls/perl-5.14.0/bin​:/home/am0c/local/android/android-sdk-linux_86/platform-tools​:/home/am0c/bin​:/home/am0c/local/android/android-sdk-linux_86/tools​:/home/am0c/bin​:/usr/local/sbin​:/usr/local/bin​:/usr/sbin​:/usr/bin​:/sbin​:/bin​:/usr/games
   PERLBREW_PATH=/home/am0c/perl5/perlbrew/bin​:/home/am0c/perl5/perlbrew/perls/perl-5.14.0/bin
   PERLBREW_PERL=perl-5.14.0
   PERLBREW_ROOT=/home/am0c/perl5/perlbrew
   PERLBREW_VERSION=0.21
   PERL_BADLANG (unset)
   SHELL=/bin/bash

[p5pRT]

From am0c@perl.kr

0001-perl-90888-each-ARRAY-on-scalar-context-should-wrapp.patch

From 329521539b6f17f285367182890c6b24a7fdf408 Mon Sep 17 00:00:00 2001
From: Hojung Yoon <amoc.yn@gmail.com>
Date: Wed, 25 May 2011 03:41:53 +0900
Subject: [PATCH] [perl #90888] each(ARRAY) on scalar context should wrapped into defined()

"perldoc -f each" says that if each() is performed on ARRAY
in scalar context, it will return only the index in an array.
Calling each(HASH) in scalar context worked well but calling
each(ARRAY) didn't because it was not wrapped into defined OPCODE.

So, in Perl_newWHILEOP() and Perl_newLOOPOP(), they are modified
to check them and wrap with defined OP if needed.

In S_new_logop(), it's reasonable to warn if return value of
each(ARRAY) is being used for boolean value, as it's first return
value will be "0", the false.

issue: #90888
link: http://rt.perl.org/rt3/Public/Bug/Display.html?id=90888
---
 op.c              |    9 ++++++---
 t/op/each_array.t |   45 +++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 49 insertions(+), 5 deletions(-)

diff --git a/op.c b/op.c
index 0d4e1e6..8d333e9 100644
--- a/op.c
+++ b/op.c
@@ -5103,7 +5103,8 @@ S_new_logop(pTHX_ I32 type, I32 flags, OP** firstp, OP** otherp)
 	    if (k1->op_type == OP_READDIR
 		  || k1->op_type == OP_GLOB
 		  || (k1->op_type == OP_NULL && k1->op_targ == OP_GLOB)
-		  || k1->op_type == OP_EACH)
+		  || k1->op_type == OP_EACH
+		  || k1->op_type == OP_AEACH)
 	    {
 		warnop = ((k1->op_type == OP_NULL)
 			  ? (OPCODE)k1->op_targ : k1->op_type);
@@ -5347,7 +5348,8 @@ Perl_newLOOPOP(pTHX_ I32 flags, I32 debuggable, OP *expr, OP *block)
 		if (k1 && (k1->op_type == OP_READDIR
 		      || k1->op_type == OP_GLOB
 		      || (k1->op_type == OP_NULL && k1->op_targ == OP_GLOB)
-		      || k1->op_type == OP_EACH))
+		      || k1->op_type == OP_EACH
+		      || k1->op_type == OP_AEACH))
 		    expr = newUNOP(OP_DEFINED, 0, expr);
 		break;
 	    }
@@ -5435,7 +5437,8 @@ Perl_newWHILEOP(pTHX_ I32 flags, I32 debuggable, LOOP *loop,
 		if (k1 && (k1->op_type == OP_READDIR
 		      || k1->op_type == OP_GLOB
 		      || (k1->op_type == OP_NULL && k1->op_targ == OP_GLOB)
-		      || k1->op_type == OP_EACH))
+		      || k1->op_type == OP_EACH
+		      || k1->op_type == OP_AEACH))
 		    expr = newUNOP(OP_DEFINED, 0, expr);
 		break;
 	    }
diff --git a/t/op/each_array.t b/t/op/each_array.t
index 2389473..9a6073a 100644
--- a/t/op/each_array.t
+++ b/t/op/each_array.t
@@ -8,9 +8,9 @@ BEGIN {
 use strict;
 use warnings;
 no warnings 'deprecated';
-use vars qw(@array @r $k $v);
+use vars qw(@array @r $k $v $c);
 
-plan tests => 48;
+plan tests => 66;
 
 @array = qw(crunch zam bloop);
 
@@ -132,3 +132,44 @@ is ("@values", "@array");
 ($k, $v) = each @array;
 is ($k, 0);
 is ($v, 'crunch');
+
+# reset
+$[ = 0;
+while (each @array) { }
+
+# each(ARRAY) in the conditional loop
+$c = 0;
+while (($k, $v) = each @array) {
+    is ($k, $c);
+    is ($v, $array[$k]);
+    $c++;
+}
+
+# each(ARRAY) on scalar context in conditional loop
+# should guarantee to be wrapped into defined() function.
+# first return value will be $[ --> [#90888]
+$c = 0;
+$k = 0;
+$v = 0;
+while ($k = each @array) {
+    is ($k, $v);
+    $v++;
+}
+
+# each(ARRAY) in the conditional loop
+$c = 0;
+for (; ($k, $v) = each @array ;) {
+    is ($k, $c);
+    is ($v, $array[$k]);
+    $c++;
+}
+
+# each(ARRAY) on scalar context in conditional loop
+# --> [#90888]
+$c = 0;
+$k = 0;
+$v = 0;
+for (; $k = each(@array) ;) {
+    is ($k, $v);
+    $v++;
+}
-- 
1.7.0.4

[p5pRT]

The RT System itself - Status changed from 'new' to 'open'

[p5pRT]

From @cpansprout

On Tue May 24 13​:15​:41 2011, am0c wrote​:

commit 329521539b6f17f285367182890c6b24a7fdf408
Author​: Hojung Yoon <amoc.yn@​gmail.com>
Date​: � Wed May 25 03​:41​:53 2011 +0900

� �[perl #90888] each(ARRAY) on scalar context should wrapped into
defined()

� �"perldoc -f each" says that if each() is performed on ARRAY
� �in scalar context, it will return only the index in an array.
� �Calling each(HASH) in scalar context worked well but calling
� �each(ARRAY) didn't because it was not wrapped into defined OPCODE.

� �So, in Perl_newWHILEOP() and Perl_newLOOPOP(), they are modified
� �to check them and wrap with defined OP if needed.

� �In S_new_logop(), it's reasonable to warn if return value of
� �each(ARRAY) is being used for boolean value, as it's first return
� �value will be "0", the false.

� �issue​: #90888
� �link​: http​://rt.perl.org/rt3/Public/Bug/Display.html?id=90888

Thank you. Applied as 459b64d.

I’m leaving this ticket open, until each $scalar is addressed.

[p5pRT]

From @jkeenan

On Tue May 24 20​:14​:26 2011, sprout wrote​:

On Tue May 24 13​:15​:41 2011, am0c wrote​:

commit 329521539b6f17f285367182890c6b24a7fdf408
Author​: Hojung Yoon <amoc.yn@​gmail.com>
Date​: � Wed May 25 03​:41​:53 2011 +0900

� �[perl #90888] each(ARRAY) on scalar context should wrapped into
defined()

� �"perldoc -f each" says that if each() is performed on ARRAY
� �in scalar context, it will return only the index in an array.
� �Calling each(HASH) in scalar context worked well but calling
� �each(ARRAY) didn't because it was not wrapped into defined OPCODE.

� �So, in Perl_newWHILEOP() and Perl_newLOOPOP(), they are modified
� �to check them and wrap with defined OP if needed.

� �In S_new_logop(), it's reasonable to warn if return value of
� �each(ARRAY) is being used for boolean value, as it's first return
� �value will be "0", the false.

� �issue​: #90888
� �link​: http​://rt.perl.org/rt3/Public/Bug/Display.html?id=90888

Thank you. Applied as 459b64d.

I’m leaving this ticket open, until each $scalar is addressed.

Does anyone know what it would take to handle the 'each $scalar' case?

Thank you very much.
Jim Keenan

[p5pRT]

From @cpansprout

On Fri Feb 15 18​:39​:02 2013, jkeenan wrote​:

On Tue May 24 20​:14​:26 2011, sprout wrote​:

On Tue May 24 13​:15​:41 2011, am0c wrote​:

commit 329521539b6f17f285367182890c6b24a7fdf408
Author​: Hojung Yoon <amoc.yn@​gmail.com>
Date​: � Wed May 25 03​:41​:53 2011 +0900

� �[perl #90888] each(ARRAY) on scalar context should wrapped into
defined()

� �"perldoc -f each" says that if each() is performed on ARRAY
� �in scalar context, it will return only the index in an array.
� �Calling each(HASH) in scalar context worked well but calling
� �each(ARRAY) didn't because it was not wrapped into defined OPCODE.

� �So, in Perl_newWHILEOP() and Perl_newLOOPOP(), they are modified
� �to check them and wrap with defined OP if needed.

� �In S_new_logop(), it's reasonable to warn if return value of
� �each(ARRAY) is being used for boolean value, as it's first return
� �value will be "0", the false.

� �issue​: #90888
� �link​: http​://rt.perl.org/rt3/Public/Bug/Display.html?id=90888

Thank you. Applied as 459b64d.

I’m leaving this ticket open, until each $scalar is addressed.

Does anyone know what it would take to handle the 'each $scalar' case?

Thank you very much.
Jim Keenan

Probably checking for OP_REACH as well as OP_AEACH.

--

Father Chrysostomos

[p5pRT]

From zefram@fysh.org

Father Chrysostomos wrote​:

Thank you. Applied as 459b64d.

I'm leaving this ticket open, until each $scalar is addressed.

The experimental each($scalar) feature has been removed. This ticket
is resolved.

-zefram

[p5pRT]

@arc - Status changed from 'open' to 'resolved'