From 64c74c4d2d2718a2059cc4dbc1626e4eb2b068db Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Tue, 25 Jan 2011 15:09:37 -0600
Subject: initial implementation

---
 dist.ini                |  1 +
 lib/circular/require.pm | 38 ++++++++++++++++++++++++++++++++++++++
 t/01-basic.t            | 40 ++++++++++++++++++++++++++++++++++++++++
 t/01/Bar.pm             |  4 ++++
 t/01/Baz.pm             |  4 ++++
 t/01/Foo.pm             |  4 ++++
 6 files changed, 91 insertions(+)
 create mode 100644 t/01-basic.t
 create mode 100644 t/01/Bar.pm
 create mode 100644 t/01/Baz.pm
 create mode 100644 t/01/Foo.pm

diff --git a/dist.ini b/dist.ini
index 1b9171c..8a4db95 100644
--- a/dist.ini
+++ b/dist.ini
@@ -7,3 +7,4 @@ copyright_holder = Jesse Luehrs
 dist = circular-require
 
 [Prereqs]
+Package::Stash = 0.22
diff --git a/lib/circular/require.pm b/lib/circular/require.pm
index e69de29..882b2b7 100644
--- a/lib/circular/require.pm
+++ b/lib/circular/require.pm
@@ -0,0 +1,38 @@
+package circular::require;
+use strict;
+use warnings;
+use Package::Stash;
+
+my %seen;
+my $saved;
+
+sub _require {
+    my ($file) = @_;
+    if (exists $seen{$file} && !$seen{$file}) {
+        warn "Circular require detected: $file (from " . caller() . ")\n";
+    }
+    $seen{$file} = 0;
+    my $ret = $saved ? $saved->($file) : CORE::require($file);
+    $seen{$file} = 1;
+    return $ret;
+}
+
+sub import {
+    my $stash = Package::Stash->new('CORE::GLOBAL');
+    if ($saved) {
+        $stash->add_package_symbol('&require' => $saved);
+    }
+    else {
+        $stash->remove_package_symbol('&require');
+    }
+}
+
+sub unimport {
+    my $stash = Package::Stash->new('CORE::GLOBAL');
+    my $old_require = $stash->get_package_symbol('&require');
+    $saved = $old_require
+        if defined($old_require) && $old_require != \&_require;
+    $stash->add_package_symbol('&require', \&_require);
+}
+
+1;
diff --git a/t/01-basic.t b/t/01-basic.t
new file mode 100644
index 0000000..5ddde3f
--- /dev/null
+++ b/t/01-basic.t
@@ -0,0 +1,40 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use lib 't/01';
+use Test::More;
+
+no circular::require;
+
+{
+    my $warnings;
+    local $SIG{__WARN__} = sub { $warnings .= $_[0] };
+    use_ok('Foo');
+    is($warnings, "Circular require detected: Foo.pm (from Baz)\nCircular require detected: Baz.pm (from Bar)\n", "correct warnings");
+    clear();
+}
+
+{
+    my $warnings;
+    local $SIG{__WARN__} = sub { $warnings .= $_[0] };
+    use_ok('Bar');
+    is($warnings, "Circular require detected: Baz.pm (from Foo)\nCircular require detected: Bar.pm (from Baz)\n", "correct warnings");
+    clear();
+}
+
+{
+    my $warnings;
+    local $SIG{__WARN__} = sub { $warnings .= $_[0] };
+    use_ok('Baz');
+    is($warnings, "Circular require detected: Baz.pm (from Foo)\n", "correct warnings");
+    clear();
+}
+
+sub clear {
+    for (qw(Foo Bar Baz)) {
+        delete $::{$_};
+        delete $INC{"$_.pm"};
+    }
+}
+
+done_testing;
diff --git a/t/01/Bar.pm b/t/01/Bar.pm
new file mode 100644
index 0000000..f7d7f72
--- /dev/null
+++ b/t/01/Bar.pm
@@ -0,0 +1,4 @@
+package Bar;
+use Baz;
+sub quux { }
+1;
diff --git a/t/01/Baz.pm b/t/01/Baz.pm
new file mode 100644
index 0000000..c70c7aa
--- /dev/null
+++ b/t/01/Baz.pm
@@ -0,0 +1,4 @@
+package Baz;
+require Foo;
+require Bar;
+1;
diff --git a/t/01/Foo.pm b/t/01/Foo.pm
new file mode 100644
index 0000000..5e5d6c3
--- /dev/null
+++ b/t/01/Foo.pm
@@ -0,0 +1,4 @@
+package Foo;
+use Baz;
+sub quux { }
+1;
-- 
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