perl-Devel-FindRef/perl-Devel-FindRef.spec

#
# spec file for package perl-Devel-FindRef
#
# Copyright (c) 2024 SUSE LLC
#
# All modifications and additions to the file contributed by third parties
# remain the property of their copyright owners, unless otherwise agreed
# upon. The license for this file, and modifications and additions to the
# file, is the same license as for the pristine package itself (unless the
# license for the pristine package is not an Open Source License, in which
# case the license is the MIT License). An "Open Source License" is a
# license that conforms to the Open Source Definition (Version 1.9)
# published by the Open Source Initiative.

# Please submit bugfixes or comments via https://bugs.opensuse.org/
#


%define cpan_name Devel-FindRef
Name:           perl-Devel-FindRef
Version:        1.460.0
Release:        0
# 1.46 -> normalize -> 1.460.0
%define cpan_version 1.46
License:        Artistic-1.0 OR GPL-1.0-or-later
Summary:        Where is that reference to my variable hiding?
URL:            https://metacpan.org/release/%{cpan_name}
Source0:        https://cpan.metacpan.org/authors/id/M/ML/MLEHMANN/%{cpan_name}-%{cpan_version}.tar.gz
Source1:        cpanspec.yml
Source100:      README.md
BuildRequires:  perl
BuildRequires:  perl-macros
BuildRequires:  perl(Canary::Stability)
BuildRequires:  perl(ExtUtils::MakeMaker) >= 6.52
BuildRequires:  perl(Task::Weaken)
BuildRequires:  perl(common::sense)
Requires:       perl(common::sense)
Provides:       perl(Devel::FindRef) = %{version}
%undefine       __perllib_provides
%{perl_requires}

%description
Tracking down reference problems (e.g. you expect some object to be
destroyed, but there are still references to it that keep it alive) can be
very hard. Fortunately, perl keeps track of all its values, so tracking
references "backwards" is usually possible.

The 'track' function can help track down some of those references back to
the variables containing them.

For example, for this fragment:

   package Test;

   use Devel::FindRef;
   use Scalar::Util;

   our $var = "hi\n";
   my $global_my = \$var;
   our %global_hash = (ukukey => \$var);
   our $global_hashref = { ukukey2 => \$var };

   sub testsub {
      my $testsub_local = $global_hashref;
      print Devel::FindRef::track \$var;
   }

   my $closure = sub {
      my $closure_var = \$_[0];
      Scalar::Util::weaken (my $weak_ref = \$var);
      testsub;
   };

   $closure->($var);

The output is as follows (or similar to this, in case I forget to update
the manpage after some changes):

   SCALAR(0x7cc888) [refcount 6] is
   +- referenced by REF(0x8abcc8) [refcount 1], which is
   |  the lexical '$closure_var' in CODE(0x8abc50) [refcount 4], which is
   |     +- the closure created at tst:18.
   |     +- referenced by REF(0x7d3c58) [refcount 1], which is
   |     |  the lexical '$closure' in CODE(0x7ae530) [refcount 2], which is
   |     |     +- the containing scope for CODE(0x8ab430) [refcount 3], which is
   |     |     |  the global &Test::testsub.
   |     |     +- the main body of the program.
   |     +- the lexical '&' in CODE(0x7ae530) [refcount 2], which was seen before.
   +- referenced by REF(0x7cc7c8) [refcount 1], which is
   |  the lexical '$global_my' in CODE(0x7ae530) [refcount 2], which was seen before.
   +- the global $Test::var.
   +- referenced by REF(0x7cc558) [refcount 1], which is
   |  the member 'ukukey2' of HASH(0x7ae140) [refcount 2], which is
   |     +- referenced by REF(0x8abad0) [refcount 1], which is
   |     |  the lexical '$testsub_local' in CODE(0x8ab430) [refcount 3], which was seen before.
   |     +- referenced by REF(0x8ab4f0) [refcount 1], which is
   |        the global $Test::global_hashref.
   +- referenced by REF(0x7ae518) [refcount 1], which is
   |  the member 'ukukey' of HASH(0x7d3bb0) [refcount 1], which is
   |     the global %Test::global_hash.
   +- referenced by REF(0x7ae2f0) [refcount 1], which is
      a temporary on the stack.

It is a bit convoluted to read, but basically it says that the value stored
in '$var' is referenced by:

* - the lexical '$closure_var' (0x8abcc8), which is inside an instantiated
  closure, which in turn is used quite a bit.

* - the package-level lexical '$global_my'.

* - the global package variable named '$Test::var'.

* - the hash element 'ukukey2', in the hash in the my variable
  '$testsub_local' in the sub 'Test::testsub' and also in the hash
  '$referenced by Test::hash2'.

* - the hash element with key 'ukukey' in the hash stored in
  '%Test::hash'.

* - some anonymous mortalised reference on the stack (which is caused
  by calling 'track' with the expression '\$var', which creates the
  reference).

And all these account for six reference counts.

%prep
%autosetup  -n %{cpan_name}-%{cpan_version}

%build
perl Makefile.PL INSTALLDIRS=vendor OPTIMIZE="%{optflags}"
%make_build

%check
make test

%install
%perl_make_install
%perl_process_packlist
%perl_gen_filelist

%files -f %{name}.files
%doc Changes README
%license COPYING

%changelog