From dpchrist at holgerdanske.com  Sat Aug  1 00:10:10 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Sat, 1 Aug 2020 00:10:10 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
Message-ID: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>

sanfrancisco-pm:

I have a Linux computer:

2020-07-31 23:24:49 dpchrist at tinkywinky ~/sandbox/perl
$ cat /etc/debian_version ; uname -a ; perl -v | head -n 3
9.13
Linux tinkywinky 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1+deb9u1 
(2020-06-07) x86_64 GNU/Linux

This is perl 5, version 24, subversion 1 (v5.24.1) built for 
x86_64-linux-gnu-thread-multi
(with 90 registered patches, see perl -V for more detail)


I am working on a Perl 5 library that uses threads.  If code in a child 
thread throws an exception, I want the exception message to be printed; 
except during testing.


I have found that:

     no warnings 'threads'

when placed before, and in the same block as, threads->create() will 
suppress printing of the exception message:

2020-07-31 23:43:08 dpchrist at tinkywinky ~/sandbox/perl
$ cat thread-exception.pl
#!perl

use strict;
use warnings;
use threads;

use Test::More;
use Test::Exception;

our $thr;
our $test_mode;

sub foo
{
     if ($test_mode) {
	no warnings 'threads';

	$thr = threads->create(
	    sub { die "hello, world!" }
	);
     } else {
	$thr = threads->create(
	    sub { die "hello, world!" }
	);
     }
}

ok foo, __FILE__ . __LINE__;				# 1

is $thr->join, undef, __FILE__ . __LINE__;		# 2

like $thr->error, qr/hello/, __FILE__ . __LINE__;	# 3

$test_mode = 1;

ok foo, __FILE__ . __LINE__;				# 4

is $thr->join, undef, __FILE__ . __LINE__;		# 5

like $thr->error, qr/hello/, __FILE__ . __LINE__;	# 6

done_testing;

2020-07-31 23:43:11 dpchrist at tinkywinky ~/sandbox/perl
$ perl thread-exception.pl
Thread 1 terminated abnormally: hello, world! at thread-exception.pl 
line 23.
ok 1 - thread-exception.pl28
ok 2 - thread-exception.pl30
ok 3 - thread-exception.pl32
ok 4 - thread-exception.pl36
ok 5 - thread-exception.pl38
ok 6 - thread-exception.pl40
1..6


I was unable to figure out how to conditionally perform "no warnings 
'threads'" in the body of foo(), so I had to copy-and-paste the body 
into both halves of an if-else conditional and disable warnings in one 
block.  This is an ugly work-around.


I was hoping for:

     no warnings 'threads' if $test_mode;	# BAD CODE


But, that code does not work;

2020-07-31 23:56:50 dpchrist at tinkywinky ~/sandbox/perl
$ cat no-warnings-threads-if-1.pl
#!perl

use strict;
use warnings;

no warnings 'threads' if 1;

2020-07-31 23:56:53 dpchrist at tinkywinky ~/sandbox/perl
$ perl no-warnings-threads-if-1.pl
syntax error at no-warnings-threads-if-1.pl line 6, near "'threads' if"
Execution of no-warnings-threads-if-1.pl aborted due to compilation errors.


Any comments or suggestions?


David

From not.com at gmail.com  Sat Aug  1 16:11:10 2020
From: not.com at gmail.com (yary)
Date: Sat, 1 Aug 2020 19:11:10 -0400
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
Message-ID: <CAG2CFAYMFTXqTq53zZw7K0f97OGF7TpZUkaZ9K9fZyZRj64+Tw@mail.gmail.com>

I think you have the condition backwards?
my $test_mode;
BEGIN { $test_mode=1 }
no if $test_mode, qw[warnings threads];



perldoc if

*NAME*

    if - "use" a Perl module if a condition holds


*SYNOPSIS*

        use if CONDITION, "MODULE", ARGUMENTS;

        no  if CONDITION, "MODULE", ARGUMENTS;

-y


On Sat, Aug 1, 2020 at 3:10 AM David Christensen <dpchrist at holgerdanske.com>
wrote:

> sanfrancisco-pm:
>
> I have a Linux computer:
>
> 2020-07-31 23:24:49 dpchrist at tinkywinky ~/sandbox/perl
> $ cat /etc/debian_version ; uname -a ; perl -v | head -n 3
> 9.13
> Linux tinkywinky 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1+deb9u1
> (2020-06-07) x86_64 GNU/Linux
>
> This is perl 5, version 24, subversion 1 (v5.24.1) built for
> x86_64-linux-gnu-thread-multi
> (with 90 registered patches, see perl -V for more detail)
>
>
> I am working on a Perl 5 library that uses threads.  If code in a child
> thread throws an exception, I want the exception message to be printed;
> except during testing.
>
>
> I have found that:
>
>      no warnings 'threads'
>
> when placed before, and in the same block as, threads->create() will
> suppress printing of the exception message:
>
> 2020-07-31 23:43:08 dpchrist at tinkywinky ~/sandbox/perl
> $ cat thread-exception.pl
> #!perl
>
> use strict;
> use warnings;
> use threads;
>
> use Test::More;
> use Test::Exception;
>
> our $thr;
> our $test_mode;
>
> sub foo
> {
>      if ($test_mode) {
>         no warnings 'threads';
>
>         $thr = threads->create(
>             sub { die "hello, world!" }
>         );
>      } else {
>         $thr = threads->create(
>             sub { die "hello, world!" }
>         );
>      }
> }
>
> ok foo, __FILE__ . __LINE__;                            # 1
>
> is $thr->join, undef, __FILE__ . __LINE__;              # 2
>
> like $thr->error, qr/hello/, __FILE__ . __LINE__;       # 3
>
> $test_mode = 1;
>
> ok foo, __FILE__ . __LINE__;                            # 4
>
> is $thr->join, undef, __FILE__ . __LINE__;              # 5
>
> like $thr->error, qr/hello/, __FILE__ . __LINE__;       # 6
>
> done_testing;
>
> 2020-07-31 23:43:11 dpchrist at tinkywinky ~/sandbox/perl
> $ perl thread-exception.pl
> Thread 1 terminated abnormally: hello, world! at thread-exception.pl
> line 23.
> ok 1 - thread-exception.pl28
> ok 2 - thread-exception.pl30
> ok 3 - thread-exception.pl32
> ok 4 - thread-exception.pl36
> ok 5 - thread-exception.pl38
> ok 6 - thread-exception.pl40
> 1..6
>
>
> I was unable to figure out how to conditionally perform "no warnings
> 'threads'" in the body of foo(), so I had to copy-and-paste the body
> into both halves of an if-else conditional and disable warnings in one
> block.  This is an ugly work-around.
>
>
> I was hoping for:
>
>      no warnings 'threads' if $test_mode;       # BAD CODE
>
>
> But, that code does not work;
>
> 2020-07-31 23:56:50 dpchrist at tinkywinky ~/sandbox/perl
> $ cat no-warnings-threads-if-1.pl
> #!perl
>
> use strict;
> use warnings;
>
> no warnings 'threads' if 1;
>
> 2020-07-31 23:56:53 dpchrist at tinkywinky ~/sandbox/perl
> $ perl no-warnings-threads-if-1.pl
> syntax error at no-warnings-threads-if-1.pl line 6, near "'threads' if"
> Execution of no-warnings-threads-if-1.pl aborted due to compilation
> errors.
>
>
> Any comments or suggestions?
>
>
> David
> _______________________________________________
> SanFrancisco-pm mailing list
> SanFrancisco-pm at pm.org
> https://mail.pm.org/mailman/listinfo/sanfrancisco-pm
>
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From doomvox at gmail.com  Sat Aug  1 16:12:33 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Sat, 1 Aug 2020 16:12:33 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
Message-ID: <CAFfgvXUkU3NEfS-tNmpn6rPLGH9UwFwvhf=HMr6otcmLziwjig@mail.gmail.com>

This sort of thing works:

my $test_mode = 0;
{
   no if $test_mode, 'uninitialized';
   my $nada = undef;
   my $string = "Nothing much: $nada";
   say "$string";
}


On 8/1/20, David Christensen <dpchrist at holgerdanske.com> wrote:
> sanfrancisco-pm:
>
> I have a Linux computer:
>
> 2020-07-31 23:24:49 dpchrist at tinkywinky ~/sandbox/perl
> $ cat /etc/debian_version ; uname -a ; perl -v | head -n 3
> 9.13
> Linux tinkywinky 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1+deb9u1
> (2020-06-07) x86_64 GNU/Linux
>
> This is perl 5, version 24, subversion 1 (v5.24.1) built for
> x86_64-linux-gnu-thread-multi
> (with 90 registered patches, see perl -V for more detail)
>
>
> I am working on a Perl 5 library that uses threads.  If code in a child
> thread throws an exception, I want the exception message to be printed;
> except during testing.
>
>
> I have found that:
>
>      no warnings 'threads'
>
> when placed before, and in the same block as, threads->create() will
> suppress printing of the exception message:
>
> 2020-07-31 23:43:08 dpchrist at tinkywinky ~/sandbox/perl
> $ cat thread-exception.pl
> #!perl
>
> use strict;
> use warnings;
> use threads;
>
> use Test::More;
> use Test::Exception;
>
> our $thr;
> our $test_mode;
>
> sub foo
> {
>      if ($test_mode) {
> 	no warnings 'threads';
>
> 	$thr = threads->create(
> 	    sub { die "hello, world!" }
> 	);
>      } else {
> 	$thr = threads->create(
> 	    sub { die "hello, world!" }
> 	);
>      }
> }
>
> ok foo, __FILE__ . __LINE__;				# 1
>
> is $thr->join, undef, __FILE__ . __LINE__;		# 2
>
> like $thr->error, qr/hello/, __FILE__ . __LINE__;	# 3
>
> $test_mode = 1;
>
> ok foo, __FILE__ . __LINE__;				# 4
>
> is $thr->join, undef, __FILE__ . __LINE__;		# 5
>
> like $thr->error, qr/hello/, __FILE__ . __LINE__;	# 6
>
> done_testing;
>
> 2020-07-31 23:43:11 dpchrist at tinkywinky ~/sandbox/perl
> $ perl thread-exception.pl
> Thread 1 terminated abnormally: hello, world! at thread-exception.pl
> line 23.
> ok 1 - thread-exception.pl28
> ok 2 - thread-exception.pl30
> ok 3 - thread-exception.pl32
> ok 4 - thread-exception.pl36
> ok 5 - thread-exception.pl38
> ok 6 - thread-exception.pl40
> 1..6
>
>
> I was unable to figure out how to conditionally perform "no warnings
> 'threads'" in the body of foo(), so I had to copy-and-paste the body
> into both halves of an if-else conditional and disable warnings in one
> block.  This is an ugly work-around.
>
>
> I was hoping for:
>
>      no warnings 'threads' if $test_mode;	# BAD CODE
>
>
> But, that code does not work;
>
> 2020-07-31 23:56:50 dpchrist at tinkywinky ~/sandbox/perl
> $ cat no-warnings-threads-if-1.pl
> #!perl
>
> use strict;
> use warnings;
>
> no warnings 'threads' if 1;
>
> 2020-07-31 23:56:53 dpchrist at tinkywinky ~/sandbox/perl
> $ perl no-warnings-threads-if-1.pl
> syntax error at no-warnings-threads-if-1.pl line 6, near "'threads' if"
> Execution of no-warnings-threads-if-1.pl aborted due to compilation errors.
>
>
> Any comments or suggestions?
>
>
> David
> _______________________________________________
> SanFrancisco-pm mailing list
> SanFrancisco-pm at pm.org
> https://mail.pm.org/mailman/listinfo/sanfrancisco-pm
>

From doomvox at gmail.com  Sat Aug  1 16:25:33 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Sat, 1 Aug 2020 16:25:33 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <CAG2CFAYMFTXqTq53zZw7K0f97OGF7TpZUkaZ9K9fZyZRj64+Tw@mail.gmail.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
 <CAG2CFAYMFTXqTq53zZw7K0f97OGF7TpZUkaZ9K9fZyZRj64+Tw@mail.gmail.com>
Message-ID: <CAFfgvXU+n+G2gXK3QKCSBf9kDED+fXK=shy1QhCrdi6me7GZpQ@mail.gmail.com>

> I think you have the condition backwards?

Could be, I didn't remember what David was going for.



On 8/1/20, yary <not.com at gmail.com> wrote:
> I think you have the condition backwards?
> my $test_mode;
> BEGIN { $test_mode=1 }
> no if $test_mode, qw[warnings threads];
>
>
>
> perldoc if
>
> *NAME*
>
>     if - "use" a Perl module if a condition holds
>
>
> *SYNOPSIS*
>
>         use if CONDITION, "MODULE", ARGUMENTS;
>
>         no  if CONDITION, "MODULE", ARGUMENTS;
>
> -y
>
>
> On Sat, Aug 1, 2020 at 3:10 AM David Christensen
> <dpchrist at holgerdanske.com>
> wrote:
>
>> sanfrancisco-pm:
>>
>> I have a Linux computer:
>>
>> 2020-07-31 23:24:49 dpchrist at tinkywinky ~/sandbox/perl
>> $ cat /etc/debian_version ; uname -a ; perl -v | head -n 3
>> 9.13
>> Linux tinkywinky 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1+deb9u1
>> (2020-06-07) x86_64 GNU/Linux
>>
>> This is perl 5, version 24, subversion 1 (v5.24.1) built for
>> x86_64-linux-gnu-thread-multi
>> (with 90 registered patches, see perl -V for more detail)
>>
>>
>> I am working on a Perl 5 library that uses threads.  If code in a child
>> thread throws an exception, I want the exception message to be printed;
>> except during testing.
>>
>>
>> I have found that:
>>
>>      no warnings 'threads'
>>
>> when placed before, and in the same block as, threads->create() will
>> suppress printing of the exception message:
>>
>> 2020-07-31 23:43:08 dpchrist at tinkywinky ~/sandbox/perl
>> $ cat thread-exception.pl
>> #!perl
>>
>> use strict;
>> use warnings;
>> use threads;
>>
>> use Test::More;
>> use Test::Exception;
>>
>> our $thr;
>> our $test_mode;
>>
>> sub foo
>> {
>>      if ($test_mode) {
>>         no warnings 'threads';
>>
>>         $thr = threads->create(
>>             sub { die "hello, world!" }
>>         );
>>      } else {
>>         $thr = threads->create(
>>             sub { die "hello, world!" }
>>         );
>>      }
>> }
>>
>> ok foo, __FILE__ . __LINE__;                            # 1
>>
>> is $thr->join, undef, __FILE__ . __LINE__;              # 2
>>
>> like $thr->error, qr/hello/, __FILE__ . __LINE__;       # 3
>>
>> $test_mode = 1;
>>
>> ok foo, __FILE__ . __LINE__;                            # 4
>>
>> is $thr->join, undef, __FILE__ . __LINE__;              # 5
>>
>> like $thr->error, qr/hello/, __FILE__ . __LINE__;       # 6
>>
>> done_testing;
>>
>> 2020-07-31 23:43:11 dpchrist at tinkywinky ~/sandbox/perl
>> $ perl thread-exception.pl
>> Thread 1 terminated abnormally: hello, world! at thread-exception.pl
>> line 23.
>> ok 1 - thread-exception.pl28
>> ok 2 - thread-exception.pl30
>> ok 3 - thread-exception.pl32
>> ok 4 - thread-exception.pl36
>> ok 5 - thread-exception.pl38
>> ok 6 - thread-exception.pl40
>> 1..6
>>
>>
>> I was unable to figure out how to conditionally perform "no warnings
>> 'threads'" in the body of foo(), so I had to copy-and-paste the body
>> into both halves of an if-else conditional and disable warnings in one
>> block.  This is an ugly work-around.
>>
>>
>> I was hoping for:
>>
>>      no warnings 'threads' if $test_mode;       # BAD CODE
>>
>>
>> But, that code does not work;
>>
>> 2020-07-31 23:56:50 dpchrist at tinkywinky ~/sandbox/perl
>> $ cat no-warnings-threads-if-1.pl
>> #!perl
>>
>> use strict;
>> use warnings;
>>
>> no warnings 'threads' if 1;
>>
>> 2020-07-31 23:56:53 dpchrist at tinkywinky ~/sandbox/perl
>> $ perl no-warnings-threads-if-1.pl
>> syntax error at no-warnings-threads-if-1.pl line 6, near "'threads' if"
>> Execution of no-warnings-threads-if-1.pl aborted due to compilation
>> errors.
>>
>>
>> Any comments or suggestions?
>>
>>
>> David
>> _______________________________________________
>> SanFrancisco-pm mailing list
>> SanFrancisco-pm at pm.org
>> https://mail.pm.org/mailman/listinfo/sanfrancisco-pm
>>
>

From dpchrist at holgerdanske.com  Sat Aug  1 18:39:01 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Sat, 1 Aug 2020 18:39:01 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <CAG2CFAYMFTXqTq53zZw7K0f97OGF7TpZUkaZ9K9fZyZRj64+Tw@mail.gmail.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
 <CAG2CFAYMFTXqTq53zZw7K0f97OGF7TpZUkaZ9K9fZyZRj64+Tw@mail.gmail.com>
Message-ID: <d810b82a-9fd3-c901-dc26-0e26bda65e1c@holgerdanske.com>

On 2020-08-01 16:11, yary wrote:
> I think you have the condition backwards?
> my $test_mode;
> BEGIN { $test_mode=1 }
> no if $test_mode, qw[warnings threads];
> 
> 
> 
> perldoc if

Thank you for directing me to conditional 'use' and 'no'.  These will be 
useful.  :-)


David

From dpchrist at holgerdanske.com  Sat Aug  1 18:40:38 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Sat, 1 Aug 2020 18:40:38 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <CAFfgvXUkU3NEfS-tNmpn6rPLGH9UwFwvhf=HMr6otcmLziwjig@mail.gmail.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
 <CAFfgvXUkU3NEfS-tNmpn6rPLGH9UwFwvhf=HMr6otcmLziwjig@mail.gmail.com>
Message-ID: <e5973ece-7590-be0b-f672-936015f4bbb4@holgerdanske.com>

On 2020-08-01 16:12, Joseph Brenner wrote:
> This sort of thing works:
> 
> my $test_mode = 0;
> {
>     no if $test_mode, 'uninitialized';
>     my $nada = undef;
>     my $string = "Nothing much: $nada";
>     say "$string";
> }

Thank you.  :-)


David

From dpchrist at holgerdanske.com  Sat Aug  1 19:12:04 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Sat, 1 Aug 2020 19:12:04 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
Message-ID: <83685025-6e5f-47ea-2598-c27db663bd27@holgerdanske.com>

On 2020-08-01 00:10, David Christensen wrote:
> sanfrancisco-pm:

> sub foo
> {
>  ??? if ($test_mode) {
>  ????no warnings 'threads';
> 
>  ????$thr = threads->create(
>  ??????? sub { die "hello, world!" }
>  ????);
>  ??? } else {
>  ????$thr = threads->create(
>  ??????? sub { die "hello, world!" }
>  ????);
>  ??? }
> }

"no warnings 'threads'" seemed overly broad, and was bugging me.


So, I came up with another approach -- use an eval-apply design pattern 
inside the child thread.  The inner code becomes an expression and fits 
into a ternary conditional.  Child errors are saved into a shared lookup 
table.  All exception messages should be caught (except those that crash 
Perl?).  Expected exception messages will pass test cases and unexpected 
messages will fail test cases:


2020-08-01 18:59:02 dpchrist at tinkywinky ~/sandbox/perl
$ cat thread-exception-eval.pl
#!perl

use strict;
use warnings;
use threads;

use Data::Dumper;
use Test::More;

our $test_mode;
our %tid_ee :shared;

sub bar { die @_ };

sub foo
{
     threads->create(
	sub {
	    my $f = shift;
     	    my $r = $test_mode
     		  ? eval { $f->(@_) }
		  : $f->(@_);
	    $tid_ee{threads->tid} = $@;
	    return $r;
	},
        	@_
     );
}

my $thr;

ok $thr = foo(\&bar, "hello, world!"), __FILE__ . __LINE__;	#  1
is $thr->join, undef, __FILE__ . __LINE__;			#  2
like $thr->error, qr/hello/, __FILE__ . __LINE__;		#  3
is $tid_ee{$thr}, undef, __FILE__ . __LINE__;			#  4

$test_mode = 1;

ok $thr = foo(\&bar, "hello, world!"), __FILE__ . __LINE__;	#  5
is $thr->join, undef, __FILE__ . __LINE__;			#  6
is $thr->error, undef, __FILE__ . __LINE__;			#  7
like $tid_ee{$thr->tid}, qr/hello/, __FILE__ . __LINE__;	#  8

ok $thr = foo(\&bar,"goodbye, cruel world!"),__FILE__.__LINE__;	#  9
is $thr->join, undef, __FILE__ . __LINE__;			# 10
is $thr->error, undef, __FILE__ . __LINE__;			# 11
like $tid_ee{$thr->tid}, qr/hello/, __FILE__ . __LINE__;	# 12

done_testing;

2020-08-01 18:59:50 dpchrist at tinkywinky ~/sandbox/perl
$ perl thread-exception-eval.pl
Thread 1 terminated abnormally: hello, world! at 
thread-exception-eval.pl line 13.
ok 1 - thread-exception-eval.pl32
ok 2 - thread-exception-eval.pl33
ok 3 - thread-exception-eval.pl34
ok 4 - thread-exception-eval.pl35
ok 5 - thread-exception-eval.pl39
ok 6 - thread-exception-eval.pl40
ok 7 - thread-exception-eval.pl41
ok 8 - thread-exception-eval.pl42
ok 9 - thread-exception-eval.pl44
ok 10 - thread-exception-eval.pl45
ok 11 - thread-exception-eval.pl46
not ok 12 - thread-exception-eval.pl47
#   Failed test 'thread-exception-eval.pl47'
#   at thread-exception-eval.pl line 47.
#                   'goodbye, cruel world! at thread-exception-eval.pl 
line 13.
# '
#     doesn't match '(?^:hello)'
1..12
# Looks like you failed 1 test of 12.


David

From not.com at gmail.com  Sun Aug  2 09:24:23 2020
From: not.com at gmail.com (yary)
Date: Sun, 2 Aug 2020 12:24:23 -0400
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <83685025-6e5f-47ea-2598-c27db663bd27@holgerdanske.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
 <83685025-6e5f-47ea-2598-c27db663bd27@holgerdanske.com>
Message-ID: <CAG2CFAYNK6RNHkiiWbG2Mgr5DfJjrqn7qgYTSjqTcftqmVtZ1w@mail.gmail.com>

Good idea, to check for expected warnings only.

This is reminding me of modules to help test warnings, looks like
https://metacpan.org/pod/Test::Warnings is the one to use these days.

Wonder what is out there to ease the eval/die testing, maybe
https://metacpan.org/pod/Test::Exception ?

-y


On Sat, Aug 1, 2020 at 10:12 PM David Christensen <dpchrist at holgerdanske.com>
wrote:

> On 2020-08-01 00:10, David Christensen wrote:
> > sanfrancisco-pm:
>
> > sub foo
> > {
> >      if ($test_mode) {
> >      no warnings 'threads';
> >
> >      $thr = threads->create(
> >          sub { die "hello, world!" }
> >      );
> >      } else {
> >      $thr = threads->create(
> >          sub { die "hello, world!" }
> >      );
> >      }
> > }
>
> "no warnings 'threads'" seemed overly broad, and was bugging me.
>
>
> So, I came up with another approach -- use an eval-apply design pattern
> inside the child thread.  The inner code becomes an expression and fits
> into a ternary conditional.  Child errors are saved into a shared lookup
> table.  All exception messages should be caught (except those that crash
> Perl?).  Expected exception messages will pass test cases and unexpected
> messages will fail test cases:
>
>
> 2020-08-01 18:59:02 dpchrist at tinkywinky ~/sandbox/perl
> $ cat thread-exception-eval.pl
> #!perl
>
> use strict;
> use warnings;
> use threads;
>
> use Data::Dumper;
> use Test::More;
>
> our $test_mode;
> our %tid_ee :shared;
>
> sub bar { die @_ };
>
> sub foo
> {
>      threads->create(
>         sub {
>             my $f = shift;
>             my $r = $test_mode
>                   ? eval { $f->(@_) }
>                   : $f->(@_);
>             $tid_ee{threads->tid} = $@;
>             return $r;
>         },
>                 @_
>      );
> }
>
> my $thr;
>
> ok $thr = foo(\&bar, "hello, world!"), __FILE__ . __LINE__;     #  1
> is $thr->join, undef, __FILE__ . __LINE__;                      #  2
> like $thr->error, qr/hello/, __FILE__ . __LINE__;               #  3
> is $tid_ee{$thr}, undef, __FILE__ . __LINE__;                   #  4
>
> $test_mode = 1;
>
> ok $thr = foo(\&bar, "hello, world!"), __FILE__ . __LINE__;     #  5
> is $thr->join, undef, __FILE__ . __LINE__;                      #  6
> is $thr->error, undef, __FILE__ . __LINE__;                     #  7
> like $tid_ee{$thr->tid}, qr/hello/, __FILE__ . __LINE__;        #  8
>
> ok $thr = foo(\&bar,"goodbye, cruel world!"),__FILE__.__LINE__; #  9
> is $thr->join, undef, __FILE__ . __LINE__;                      # 10
> is $thr->error, undef, __FILE__ . __LINE__;                     # 11
> like $tid_ee{$thr->tid}, qr/hello/, __FILE__ . __LINE__;        # 12
>
> done_testing;
>
> 2020-08-01 18:59:50 dpchrist at tinkywinky ~/sandbox/perl
> $ perl thread-exception-eval.pl
> Thread 1 terminated abnormally: hello, world! at
> thread-exception-eval.pl line 13.
> ok 1 - thread-exception-eval.pl32
> ok 2 - thread-exception-eval.pl33
> ok 3 - thread-exception-eval.pl34
> ok 4 - thread-exception-eval.pl35
> ok 5 - thread-exception-eval.pl39
> ok 6 - thread-exception-eval.pl40
> ok 7 - thread-exception-eval.pl41
> ok 8 - thread-exception-eval.pl42
> ok 9 - thread-exception-eval.pl44
> ok 10 - thread-exception-eval.pl45
> ok 11 - thread-exception-eval.pl46
> not ok 12 - thread-exception-eval.pl47
> #   Failed test 'thread-exception-eval.pl47'
> #   at thread-exception-eval.pl line 47.
> #                   'goodbye, cruel world! at thread-exception-eval.pl
> line 13.
> # '
> #     doesn't match '(?^:hello)'
> 1..12
> # Looks like you failed 1 test of 12.
>
>
> David
> _______________________________________________
> SanFrancisco-pm mailing list
> SanFrancisco-pm at pm.org
> https://mail.pm.org/mailman/listinfo/sanfrancisco-pm
>
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From doomvox at gmail.com  Sun Aug  2 14:51:06 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Sun, 2 Aug 2020 14:51:06 -0700
Subject: [sf-perl] more zooming about Raku
Message-ID: <CAFfgvXXyPADfx0-NBeOpQ3-aCo-q01ztB-ia6w1+-EDR_9Bu8g@mail.gmail.com>

Joseph Brenner is inviting you to a scheduled Zoom meeting.

Topic: Raku aka Perl6 Study Group #2
Time: Aug 2, 2020 03:00 PM Pacific Time (US and Canada)

Join Zoom Meeting
https://us04web.zoom.us/j/74244162263?pwd=eTQ0TUt5YmxUN3FCVjI0RXhReXhUZz09

Meeting ID: 742 4416 2263
Passcode: 4RakuRoll

From doomvox at gmail.com  Sun Aug  2 14:53:47 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Sun, 2 Aug 2020 14:53:47 -0700
Subject: [sf-perl] more zooming about Raku
In-Reply-To: <CAFfgvXXyPADfx0-NBeOpQ3-aCo-q01ztB-ia6w1+-EDR_9Bu8g@mail.gmail.com>
References: <CAFfgvXXyPADfx0-NBeOpQ3-aCo-q01ztB-ia6w1+-EDR_9Bu8g@mail.gmail.com>
Message-ID: <CAFfgvXWWidP-EbbXju7eFYN8S4YTuC7B3W8pOTCVN5RheTo3kw@mail.gmail.com>

And at 4pm, just in case:


https://us04web.zoom.us/j/75254368231?pwd=Q0JwNnB3Mmoyc1I3V3JpV1RnSHRndz09



On 8/2/20, Joseph Brenner <doomvox at gmail.com> wrote:
> Joseph Brenner is inviting you to a scheduled Zoom meeting.
>
> Topic: Raku aka Perl6 Study Group #2
> Time: Aug 2, 2020 03:00 PM Pacific Time (US and Canada)
>
> Join Zoom Meeting
> https://us04web.zoom.us/j/74244162263?pwd=eTQ0TUt5YmxUN3FCVjI0RXhReXhUZz09
>
> Meeting ID: 742 4416 2263
> Passcode: 4RakuRoll
>

From dpchrist at holgerdanske.com  Sun Aug  2 16:40:14 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Sun, 2 Aug 2020 16:40:14 -0700
Subject: [sf-perl] conditional "no warnings 'threads'"
In-Reply-To: <CAG2CFAYNK6RNHkiiWbG2Mgr5DfJjrqn7qgYTSjqTcftqmVtZ1w@mail.gmail.com>
References: <1b4d7da1-75cb-100b-781f-b7feef345728@holgerdanske.com>
 <83685025-6e5f-47ea-2598-c27db663bd27@holgerdanske.com>
 <CAG2CFAYNK6RNHkiiWbG2Mgr5DfJjrqn7qgYTSjqTcftqmVtZ1w@mail.gmail.com>
Message-ID: <2f0968cc-d616-6495-7d1a-30d93a28fe96@holgerdanske.com>

On 2020-08-02 09:24, yary wrote:

> This is reminding me of modules to help test warnings, looks like
> https://metacpan.org/pod/Test::Warnings is the one to use these days.
> 
> Wonder what is out there to ease the eval/die testing, maybe
> https://metacpan.org/pod/Test::Exception ?

Please "reply to list".


Yes, I tried both.  They do not seem to be designed for test scripts 
running in the main thread and the unit under test (UUT) running in a 
different thread.


I thought about moving the test scripts into the same thread as the UUT, 
or vice-versa.  Some test cases can be done entirely in the main thread, 
so I did that.  But other test cases are testing multi-threaded 
behavior, so I needed new ideas.


threads::error() provides the child exception message to the test 
script, so I could test my UUT exceptions.  But, the exception messages 
were leaking to the console.  The conditional "no warnings 'threads'" 
was a hack to stop the leaks.  The subsequent eval-apply idea is better. 
  (It should probably be called "eval-catch".)


For warnings, I implemented a shim function.  threads::create() calls 
the shim.  The shim installs a $SIG{__WARN__} handler and calls the 
child entry function.  The handler saves any child warning messages into 
a shared variable.  The test script examines the shared variable.


I am now adding the eval-catch idea to the shim.  I also plan to change 
the shim from fixed handlers and shared variables to callbacks.


David

From dean at fragfest.com.au  Wed Aug  5 13:32:49 2020
From: dean at fragfest.com.au (Dean Hamstead)
Date: Wed, 05 Aug 2020 13:32:49 -0700
Subject: [sf-perl] Survey: Marketing and branding for The Perl Foundation
 (TPF)
Message-ID: <7201e552f06e00a5d29ce0fdccb694b2@fragfest.com.au>

Hey Everyone

The Marketing Committee of TPF would like to understand more about your 
perception of "The Perl Foundation"[1] itself (rather than Perl the 
language) and has posted a survey.

If you are not programming Perl or Raku anymore, your input is still 
welcomed.
If you have not familiar with The Perl Foundation, please fill out the 
survey accordingly.

And in all cases, you're welcome to fill out the "Other" field if 
another response doesn't suit.


Here is the link:

https://docs.google.com/forms/d/e/1FAIpQLSdGwTCV8TIELW1tYkYv2Sl-z7uSCthXB0XfN2TGTrQftCz2Kw/viewform


Please forward to your colleagues, friends, etc.


Cheers,

Dean

1. https://www.perlfoundation.org/

From doomvox at gmail.com  Sat Aug  8 16:20:41 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Sat, 8 Aug 2020 16:20:41 -0700
Subject: [sf-perl] Raku study group, Sunday Aug 8nd, 2pm
Message-ID: <CAFfgvXXuENj6EeYM5dRe1MDzfHQ1TiW82vzGkDz5jivCDMDRdA@mail.gmail.com>

And once again, the creature from the Raku study group emerges:

Sunday August 09th at 2pm, via zoom.

RSVP to:
https://www.meetup.com/San-Francisco-Perl/events/271993517/

zoom link, 2pm:
https://us04web.zoom.us/j/72909473784?pwd=YTd1ZnlWTFV3ckZMWmtRcXdPK2loZz09

From dpchrist at holgerdanske.com  Tue Aug 11 16:55:14 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Tue, 11 Aug 2020 16:55:14 -0700
Subject: [sf-perl] Perl references to arrays vs. references to shared arrays
Message-ID: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>

sanfrancisco-pm:

I have a computer:

2020-08-11 16:02:50 dpchrist at tinkywinky ~/sandbox/perl
$ cat /etc/debian_version ; uname -a ; perl -V | head -n 1
9.13
Linux tinkywinky 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1+deb9u1 
(2020-06-07) x86_64 GNU/Linux
Summary of my perl5 (revision 5 version 24 subversion 1) configuration:


I have been working with nested data structures.  Some data structures 
can contain loops -- e.g. a data structure that contains a reference to 
itself, a data structure that contains a reference to another data 
structure that refers to the first data structure, etc.


To detect circular loops, I need a way to uniquely identify each data 
structure.  I have noted that if I stringify a reference to a data 
structure, the result appears to be the type and a hexadecimal memory 
address.  For example:

2020-08-11 16:09:21 dpchrist at tinkywinky ~/sandbox/perl
$ perl -e 'my @a; print \@a, "\n"'
ARRAY(0x55d9a7410be0)


This also works if another data structure contains a reference to the first:

2020-08-11 16:35:31 dpchrist at tinkywinky ~/sandbox/perl
$ perl -e 'my (@a, @b); print \@a, "\n"; $b[0] = \@a; print $b[0], "\n"'
ARRAY(0x55b10cedbc10)
ARRAY(0x55b10cedbc10)


But the technique fails for data structures built from shared variables. 
  It appears that Perl is copying and/or moving shared arrays, hashes, 
etc., whenever their references are accessed (read):

2020-08-11 16:18:39 dpchrist at tinkywinky ~/sandbox/perl
$ cat circular-arrayref-vs-shared-arrayref.pl
#!perl

use strict;
use warnings;
use threads;
use threads::shared;

my @a0;
my @a1;

my @sa0 :shared;
my @sa1 :shared;

sub d {
     no warnings 'uninitialized';
     printf "%i %s=[%21s] %s=[%21s]\n",
	(caller)[2], \@a0, $a0[0], \@a1, $a1[0];
}

sub e {
     no warnings 'uninitialized';
     printf "%i %s=[%21s] %s=[%21s]\n",
	(caller)[2], \@sa0, $sa0[0], \@sa1, $sa1[0];
}

print "\nArrays with circular references:\n";
				d; d; d;
$a0[0]  = \@a1;			d; d; d;
$a1[0]  = \@a0;			d; d; d;

print "\nShared arrays with circular references:\n";
				e; e; e;
$sa0[0] = \@sa1;		e; e; e;
$sa1[0] = \@sa0;		e; e; e;

2020-08-11 16:18:42 dpchrist at tinkywinky ~/sandbox/perl
$ perl circular-arrayref-vs-shared-arrayref.pl

Arrays with circular references:
27 ARRAY(0x5569415e7df8)=[                     ] ARRAY(0x5569415e7d80)=[ 
                     ]
27 ARRAY(0x5569415e7df8)=[                     ] ARRAY(0x5569415e7d80)=[ 
                     ]
27 ARRAY(0x5569415e7df8)=[                     ] ARRAY(0x5569415e7d80)=[ 
                     ]
28 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] ARRAY(0x5569415e7d80)=[ 
                     ]
28 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] ARRAY(0x5569415e7d80)=[ 
                     ]
28 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] ARRAY(0x5569415e7d80)=[ 
                     ]
29 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] 
ARRAY(0x5569415e7d80)=[ARRAY(0x5569415e7df8)]
29 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] 
ARRAY(0x5569415e7d80)=[ARRAY(0x5569415e7df8)]
29 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] 
ARRAY(0x5569415e7d80)=[ARRAY(0x5569415e7df8)]

Shared arrays with circular references:
32 ARRAY(0x5569415e7de0)=[                     ] ARRAY(0x5569415e7e70)=[ 
                     ]
32 ARRAY(0x5569415e7de0)=[                     ] ARRAY(0x5569415e7e70)=[ 
                     ]
32 ARRAY(0x5569415e7de0)=[                     ] ARRAY(0x5569415e7e70)=[ 
                     ]
33 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de0d8)] ARRAY(0x5569415e7e70)=[ 
                     ]
33 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de048)] ARRAY(0x5569415e7e70)=[ 
                     ]
33 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416a00c0)] ARRAY(0x5569415e7e70)=[ 
                     ]
34 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de048)] 
ARRAY(0x5569415e7e70)=[ARRAY(0x556941690c40)]
34 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416a00c0)] 
ARRAY(0x5569415e7e70)=[ARRAY(0x556941690c58)]
34 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de048)] 
ARRAY(0x5569415e7e70)=[ARRAY(0x556941690c88)]


For the non-shared arrays, the stringified references are unchanging and 
match up -- e.g. both \@a0 and $a1[0] stringify to 
ARRAY(0x5569415e7df8), similarly so for \@a1 and $a0[0].


But the stringified references for shared types do not match, and the 
references in another data structure change -- \@sa0 stringifies to 
ARRAY(0x5569415e7de0) every time, but what should be the same reference 
in $sa1[0] stringifies to ARRAY(0x556941690c40, ARRAY(0x556941690c58, 
and ARRAY(0x556941690c88 (!).  Similarly so for \@sa1 and $sa0[0]. 
Consequently, loop detection fails and my code falls into an infinite 
loop when walking such data structures.


Comments or suggestions?


David

From doomvox at gmail.com  Thu Aug 13 14:01:01 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Thu, 13 Aug 2020 14:01:01 -0700
Subject: [sf-perl] Perl references to arrays vs. references to shared
 arrays
In-Reply-To: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>
References: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>
Message-ID: <CAFfgvXW_qXbL40_W2_oML7Gm0HdW3teuBKu=-ThkMPX8TAdACA@mail.gmail.com>

Well, the result you've found is pretty much what I would've expected
from other things I've heard...

For example, back when people were experimenting a lot with "inside
out objects", which use the stringified form of a scalar ref as an
object ID, the word was that this had problems if you were trying to
use threads.   That was supposed to be a problem with Damien Conway's
"Class::Std", for example.

I see that Class::InsideOut and Object::InsideOut both claim to be threadsafe:

  https://metacpan.org/pod/Class::InsideOut
  https://metacpan.org/pod/distribution/Object-InsideOut/lib/Object/InsideOut.pod#THREAD-SUPPORT#

You might take a look under the hood there to see how they manage
it...  I would guess if you're rolling your own object system it's
relatively easy to deal, you'd just need your own system of unique IDs
for each object.

I would think you could do pretty well with just a probablistic
solution where collisions are extremely unlikely, like combining a
memory location, the current time in seconds, and a "random" number.

Alternately, if you have some sort of central data store for node ids,
you could check for collisions when you create them, but then you need
to worry about how you're going to handle race-conditions.

(One reason I like relational databases is that most headaches like
these have been handled already by someone else.)

But this all depends on being willing to munge your data-structure,
and store a node Id in them somewhere.

If you didn't want to go there, it occurs to me that if you're just
trying to detect circular references you could check many times (1000?
More?) and call it circular if you find a loop just once.  Oddities
with threads might cause a detection failure *some* times, but I don't
think they'd do so consistently, would they?

(Interestingly, Conway's more recent attempt Dios doesn't seem to say
anything about thread support: https://metacpan.org/pod/Dios).


On 8/11/20, David Christensen <dpchrist at holgerdanske.com> wrote:
> sanfrancisco-pm:
>
> I have a computer:
>
> 2020-08-11 16:02:50 dpchrist at tinkywinky ~/sandbox/perl
> $ cat /etc/debian_version ; uname -a ; perl -V | head -n 1
> 9.13
> Linux tinkywinky 4.9.0-12-amd64 #1 SMP Debian 4.9.210-1+deb9u1
> (2020-06-07) x86_64 GNU/Linux
> Summary of my perl5 (revision 5 version 24 subversion 1) configuration:
>
>
> I have been working with nested data structures.  Some data structures
> can contain loops -- e.g. a data structure that contains a reference to
> itself, a data structure that contains a reference to another data
> structure that refers to the first data structure, etc.
>
>
> To detect circular loops, I need a way to uniquely identify each data
> structure.  I have noted that if I stringify a reference to a data
> structure, the result appears to be the type and a hexadecimal memory
> address.  For example:
>
> 2020-08-11 16:09:21 dpchrist at tinkywinky ~/sandbox/perl
> $ perl -e 'my @a; print \@a, "\n"'
> ARRAY(0x55d9a7410be0)
>
>
> This also works if another data structure contains a reference to the
> first:
>
> 2020-08-11 16:35:31 dpchrist at tinkywinky ~/sandbox/perl
> $ perl -e 'my (@a, @b); print \@a, "\n"; $b[0] = \@a; print $b[0], "\n"'
> ARRAY(0x55b10cedbc10)
> ARRAY(0x55b10cedbc10)
>
>
> But the technique fails for data structures built from shared variables.
>   It appears that Perl is copying and/or moving shared arrays, hashes,
> etc., whenever their references are accessed (read):
>
> 2020-08-11 16:18:39 dpchrist at tinkywinky ~/sandbox/perl
> $ cat circular-arrayref-vs-shared-arrayref.pl
> #!perl
>
> use strict;
> use warnings;
> use threads;
> use threads::shared;
>
> my @a0;
> my @a1;
>
> my @sa0 :shared;
> my @sa1 :shared;
>
> sub d {
>      no warnings 'uninitialized';
>      printf "%i %s=[%21s] %s=[%21s]\n",
> 	(caller)[2], \@a0, $a0[0], \@a1, $a1[0];
> }
>
> sub e {
>      no warnings 'uninitialized';
>      printf "%i %s=[%21s] %s=[%21s]\n",
> 	(caller)[2], \@sa0, $sa0[0], \@sa1, $sa1[0];
> }
>
> print "\nArrays with circular references:\n";
> 				d; d; d;
> $a0[0]  = \@a1;			d; d; d;
> $a1[0]  = \@a0;			d; d; d;
>
> print "\nShared arrays with circular references:\n";
> 				e; e; e;
> $sa0[0] = \@sa1;		e; e; e;
> $sa1[0] = \@sa0;		e; e; e;
>
> 2020-08-11 16:18:42 dpchrist at tinkywinky ~/sandbox/perl
> $ perl circular-arrayref-vs-shared-arrayref.pl
>
> Arrays with circular references:
> 27 ARRAY(0x5569415e7df8)=[                     ] ARRAY(0x5569415e7d80)=[
>                      ]
> 27 ARRAY(0x5569415e7df8)=[                     ] ARRAY(0x5569415e7d80)=[
>                      ]
> 27 ARRAY(0x5569415e7df8)=[                     ] ARRAY(0x5569415e7d80)=[
>                      ]
> 28 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] ARRAY(0x5569415e7d80)=[
>                      ]
> 28 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] ARRAY(0x5569415e7d80)=[
>                      ]
> 28 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)] ARRAY(0x5569415e7d80)=[
>                      ]
> 29 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)]
> ARRAY(0x5569415e7d80)=[ARRAY(0x5569415e7df8)]
> 29 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)]
> ARRAY(0x5569415e7d80)=[ARRAY(0x5569415e7df8)]
> 29 ARRAY(0x5569415e7df8)=[ARRAY(0x5569415e7d80)]
> ARRAY(0x5569415e7d80)=[ARRAY(0x5569415e7df8)]
>
> Shared arrays with circular references:
> 32 ARRAY(0x5569415e7de0)=[                     ] ARRAY(0x5569415e7e70)=[
>                      ]
> 32 ARRAY(0x5569415e7de0)=[                     ] ARRAY(0x5569415e7e70)=[
>                      ]
> 32 ARRAY(0x5569415e7de0)=[                     ] ARRAY(0x5569415e7e70)=[
>                      ]
> 33 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de0d8)] ARRAY(0x5569415e7e70)=[
>                      ]
> 33 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de048)] ARRAY(0x5569415e7e70)=[
>                      ]
> 33 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416a00c0)] ARRAY(0x5569415e7e70)=[
>                      ]
> 34 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de048)]
> ARRAY(0x5569415e7e70)=[ARRAY(0x556941690c40)]
> 34 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416a00c0)]
> ARRAY(0x5569415e7e70)=[ARRAY(0x556941690c58)]
> 34 ARRAY(0x5569415e7de0)=[ARRAY(0x5569416de048)]
> ARRAY(0x5569415e7e70)=[ARRAY(0x556941690c88)]
>
>
> For the non-shared arrays, the stringified references are unchanging and
> match up -- e.g. both \@a0 and $a1[0] stringify to
> ARRAY(0x5569415e7df8), similarly so for \@a1 and $a0[0].
>
>
> But the stringified references for shared types do not match, and the
> references in another data structure change -- \@sa0 stringifies to
> ARRAY(0x5569415e7de0) every time, but what should be the same reference
> in $sa1[0] stringifies to ARRAY(0x556941690c40, ARRAY(0x556941690c58,
> and ARRAY(0x556941690c88 (!).  Similarly so for \@sa1 and $sa0[0].
> Consequently, loop detection fails and my code falls into an infinite
> loop when walking such data structures.
>
>
> Comments or suggestions?
>
>
> David
> _______________________________________________
> SanFrancisco-pm mailing list
> SanFrancisco-pm at pm.org
> https://mail.pm.org/mailman/listinfo/sanfrancisco-pm
>

From dpchrist at holgerdanske.com  Thu Aug 13 18:05:47 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Thu, 13 Aug 2020 18:05:47 -0700
Subject: [sf-perl] Perl references to arrays vs. references to shared
 arrays
In-Reply-To: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>
References: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>
Message-ID: <dea9bde1-0790-1eb4-755d-abbfae2dd2cd@holgerdanske.com>

On 2020-08-11 16:55, David Christensen wrote:

> I have been working with nested data structures.

> To detect circular loops ... stringify a reference

> But the technique fails for data structures built from shared variables.


The solution is to use shared::threads::is_shared:

     https://metacpan.org/pod/threads::shared


In the example below, I used Scalar::Util::refaddr for consistency:


2020-08-13 18:00:18 dpchrist at tinkywinky ~/sandbox/perl
$ cat circular-arrayref-vs-shared-arrayref.pl
#!perl

use strict;
use warnings;
use threads;
use threads::shared;

use Scalar::Util		qw( refaddr );

my @a0;
my @a1;

my @sa0 :shared;
my @sa1 :shared;

sub d {
     no warnings 'uninitialized';
     printf "%i %s=[%21s] %s=[%21s]\n",
	(caller)[2],
        	refaddr(\@a0), refaddr($a0[0]),
        	refaddr(\@a1), refaddr($a1[0]);
}

sub e {
     no warnings 'uninitialized';
     printf "%i %s=[%21s] %s=[%21s]\n",
	(caller)[2],
        	is_shared(@sa0), is_shared($sa0[0]),
        	is_shared(@sa1), is_shared($sa1[0]);
}

print "\nArrays with circular references:\n";
				d; d; d;
$a0[0]  = \@a1;			d; d; d;
$a1[0]  = \@a0;			d; d; d;

print "\nShared arrays with circular references:\n";
				e; e; e;
$sa0[0] = \@sa1;		e; e; e;
$sa1[0] = \@sa0;		e; e; e;

2020-08-13 18:00:22 dpchrist at tinkywinky ~/sandbox/perl
$ perl circular-arrayref-vs-shared-arrayref.pl

Arrays with circular references:
33 93884874649056=[                     ] 93884874649128=[ 
       ]
33 93884874649056=[                     ] 93884874649128=[ 
       ]
33 93884874649056=[                     ] 93884874649128=[ 
       ]
34 93884874649056=[       93884874649128] 93884874649128=[ 
       ]
34 93884874649056=[       93884874649128] 93884874649128=[ 
       ]
34 93884874649056=[       93884874649128] 93884874649128=[ 
       ]
35 93884874649056=[       93884874649128] 93884874649128=[ 
93884874649056]
35 93884874649056=[       93884874649128] 93884874649128=[ 
93884874649056]
35 93884874649056=[       93884874649128] 93884874649128=[ 
93884874649056]

Shared arrays with circular references:
38 93884875574272=[                     ] 93884875574296=[ 
       ]
38 93884875574272=[                     ] 93884875574296=[ 
       ]
38 93884875574272=[                     ] 93884875574296=[ 
       ]
39 93884875574272=[       93884875574296] 93884875574296=[ 
       ]
39 93884875574272=[       93884875574296] 93884875574296=[ 
       ]
39 93884875574272=[       93884875574296] 93884875574296=[ 
       ]
40 93884875574272=[       93884875574296] 93884875574296=[ 
93884875574272]
40 93884875574272=[       93884875574296] 93884875574296=[ 
93884875574272]
40 93884875574272=[       93884875574296] 93884875574296=[ 
93884875574272]


David

From dpchrist at holgerdanske.com  Thu Aug 13 18:53:43 2020
From: dpchrist at holgerdanske.com (David Christensen)
Date: Thu, 13 Aug 2020 18:53:43 -0700
Subject: [sf-perl] Perl references to arrays vs. references to shared
 arrays
In-Reply-To: <CAFfgvXW_qXbL40_W2_oML7Gm0HdW3teuBKu=-ThkMPX8TAdACA@mail.gmail.com>
References: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>
 <CAFfgvXW_qXbL40_W2_oML7Gm0HdW3teuBKu=-ThkMPX8TAdACA@mail.gmail.com>
Message-ID: <e9cde38c-fa5b-3b60-7ebe-335c46dc101b@holgerdanske.com>

On 2020-08-13 14:01, Joseph Brenner wrote:
> Well, the result you've found is pretty much what I would've expected
> from other things I've heard...

Thanks for the reply.  :-)


I pondered some of those ideas.  Thankfully, I was RTFM threads:shared 
on a related issue and found a solution.


David

From doomvox at gmail.com  Fri Aug 14 09:26:58 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Fri, 14 Aug 2020 09:26:58 -0700
Subject: [sf-perl] Perl references to arrays vs. references to shared
 arrays
In-Reply-To: <dea9bde1-0790-1eb4-755d-abbfae2dd2cd@holgerdanske.com>
References: <d74539fa-33e9-2632-e99b-27ab3eed4c10@holgerdanske.com>
 <dea9bde1-0790-1eb4-755d-abbfae2dd2cd@holgerdanske.com>
Message-ID: <CAFfgvXVr5EfdgtKP1ZXG26q6BBBsEX8mCQ_ci2DNvfsheK9O1g@mail.gmail.com>

David Christensen <dpchrist at holgerdanske.com> wrote:
> The solution is to use shared::threads::is_shared:

>    https://metacpan.org/pod/threads::shared

Ah, very cool, hadn't heard about that trick.

From doomvox at gmail.com  Fri Aug 14 10:21:49 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Fri, 14 Aug 2020 10:21:49 -0700
Subject: [sf-perl] The Raku Study Group, at 1pm this time, on Sunday the 16th
Message-ID: <CAFfgvXUsrnWPSccfhNfLcOJ-mz5W2kuZsR=NGfz12UXVHhwxHw@mail.gmail.com>

"The world is full of magical things patiently waiting for our
wits to grow sharper." [1]   Time for another Raku study group:

https://us02web.zoom.us/j/86928085691?pwd=bWZ5TzNWbFlTaFpOWVloU3NXUEIrdz09

Password: 4RakuRoll

Note: we're experimenting with an earlier start time, 1pm PST, to
make things a little easier for people in europe.

RSVP, if you're so inclined:

https://www.meetup.com/San-Francisco-Perl/events/272577658/

[1] Attributed to Bertrand Russell at
https://www.success.com/21-of-the-most-inspirational-quotes/

Probably a paraphrase of Eden Phillpotts, "A Shadow Passes" (1919):
https://quoteinvestigator.com/2012/07/07/magical-things-waiting/

From doomvox at gmail.com  Tue Aug 18 14:38:22 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Tue, 18 Aug 2020 14:38:22 -0700
Subject: [sf-perl] SF Perl's Raku Study Group: Sunday 1pm PST
Message-ID: <CAFfgvXWTzAhYJ4t+xVAdQPODzOxZbVsiqv-3W7C8rGw1JUUQew@mail.gmail.com>

Yeaning for the ancient heavenly connection to the starry dynamo
of night, it's the Raku study group:

https://us02web.zoom.us/j/85864767082?pwd=TW94dG8zR2tHWEl3ZVdvdmVyYkJkUT09

Password: 4RakuRoll.

Note: we're  using an earlier start time now, 1pm PST, to
make things a little easier for people in Europe (e.g. that's 10pm in Berlin).

RSVP if you're so inclined:

https://www.meetup.com/San-Francisco-Perl/events/272661690/

From doomvox at gmail.com  Fri Aug 28 00:20:35 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Fri, 28 Aug 2020 00:20:35 -0700
Subject: [sf-perl] perl6-users@perl.org, sanfrancisco-pm@pm.org
Message-ID: <CAFfgvXV5epizk_YxWyrstB8CEUS=AwtAN1G=JE7b-5iV4DSxmQ@mail.gmail.com>

Deep into that darkness peering, long I stood there, wondering,
fearing, doubting, dreaming dreams of the Raku Study Group.

https://us02web.zoom.us/j/88495193366?pwd=TXpMSlVqaVVGMm52SWlvSmRrZXFBUT09

Password: 4RakuRoll

Note: we're still using that earlier start time: 1pm in California.
This makes things a little easier for people in Europe (that start
time is 10pm in Berlin).

RSVPs are helpful (though not required):

https://www.meetup.com/San-Francisco-Perl/events/272865558/

From doomvox at gmail.com  Sun Aug 30 13:43:16 2020
From: doomvox at gmail.com (Joseph Brenner)
Date: Sun, 30 Aug 2020 13:43:16 -0700
Subject: [sf-perl] Raku Study group in progress
Message-ID: <CAFfgvXUTikQ9yYsRX4qpUaZ=Vu+fKR8uT2ZbLPHCACdepQAE-Q@mail.gmail.com>

I'm trying to get the Raku study group working today, but I've
been having a bunch of zoom weirdness.  It should be in progress
now:


The SF Perl Raku Study Group, 8/30 at 1pm PDT

https://us02web.zoom.us/j/88495193366?pwd=TXpMSlVqaVVGMm52SWlvSmRrZXFBUT09

Password: 4RakuRoll