How to rename perl __ANON__ sub without disabling strict 'refs'? - perl

Question

I found a solution to renaming anonymous subs in Perl here. It involves temporarily mangling the symbol table to insert the desired name. This solution uses a hard-coded symbol table name to be replaced. My problem is that I would like to dynamically choose the symbol table name at runtime. Something like this:
$pkg = 'MyPkg::ModA::';
$name = 'subname';
...
no strict 'refs';
local *{"${pkg}__ANON__"} = "$name [anon]";
strict refs;
The only way to make it work is to disable strict refs. If they are not disabled, the script fails with this message:
Can't use string ("MyPkg::ModA::__ANON__") as a symbol ref while "strict refs" in use at /path/to/source/File.pm line xx
Note that the equivalent statement could be used
local ${$pkg}{__ANON__} = "$name [anon]";
with the similar error message:
Can't use string ("MyPkg::ModA::") as a HASH ref while "strict refs" in use at /path/to/source/File.pm line xx
Is it possible to do the same thing without disabling strict refs?
TMI/DNR:
Here is a complete example in case you're interested. Ironically, my solution uses an anonymous sub to rename the given anonymous sub.
ModA.pm
package MyPkg::ModA;
use strict;
use warnings;
use MyPkg::Util;
# Create a new instance.
sub new
{
my ($type, $class, $self);
# allow for both ModA::new and $moda->new
$type = shift;
$class = ref $type || $type;
$self = {#_};
bless $self, $class;
# use exported Util::anon sub here
$self->{func} = anon sub
{
my ($arg);
$arg = shift;
debug "\$arg: $arg";
};
return $self;
} # new
1;
__END__
ModB.pm
package MyPkg::ModB;
use strict;
use warnings;
use MyPkg::ModA;
# Create a new instance.
sub new
{
my ($type, $class, $self);
# allow for both ModB::new and $modb->new
$type = shift;
$class = ref $type || $type;
$self = {#_};
bless $self, $class;
$self->{modA} = MyPkg::ModA->new;
return $self;
} # new
# Do something with ModA.
sub doit
{
my ($self);
$self = shift;
$self->{modA}->{func}->('What is your quest?');
} # doit
1;
__END__
Util.pm
package MyPkg::Util;
use strict;
use warnings;
require Exporter;
our (#ISA, #EXPORT);
#ISA = qw(Exporter);
#EXPORT = qw(
anon
debug);
# Temporarily mangle symbol table to replace '__ANON__'.
sub anon
{
my ($func, $sub, $pkg, $name);
$func = shift;
$sub = (caller 1)[3];
$sub =~ /(.*::)(.+)/;
$pkg = $1;
$name = $2;
return sub
{
# TODO How to do this w/o disabling strict?
#no strict 'refs';
# temp symbol table mangling here
# ${$pkg}{__ANON__} is equivalent to *{"${pkg}__ANON__"}
local *{"${pkg}__ANON__"} = "$name [anon]";
use strict;
$func->(#_);
};
} # anon
# Print a debug message.
sub debug
{
my($fname, $line, $sub);
($fname, $line) = (caller 0)[1,2];
$fname =~ s/.+\///;
$sub = (caller 1)[3] || 'main';
$sub =~ s/.*::(.+)/$1/;
printf STDERR "%-10s %s(%s) - \"%s\"\n", $fname, $sub, $line, "#_";
} # debug
1;
__END__
mytest.pl
#! /usr/bin/perl
use strict;
use warnings;
use MyPkg::ModB;
# Stuff happens here.
my ($modB);
$modB = MyPkg::ModB->new;
$modB->doit;

Answer 1

You can use core module Sub::Util's set_subname.
use Sub::Util qw( set_subname );
sub anon {
...
return set_subname("$name [anon]", $func);
}