From 64efe5712156c98feb7372915a0d90bb639eee6a Mon Sep 17 00:00:00 2001
From: Lars Wirzenius <liw@liw.fi>
Date: Tue, 28 Mar 2017 17:27:16 +0300
Subject: Implement implicitly persistent variable storage

---
 fail-tests/fail.stdout-diff |  2 +-
 yarnutils/__init__.py       |  1 +
 yarnutils/vars.py           | 47 +++++++++++++++++++++++++++++++++++++++++++++
 yarnutils/vars_tests.py     | 43 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 92 insertions(+), 1 deletion(-)
 create mode 100644 yarnutils/vars.py
 create mode 100644 yarnutils/vars_tests.py

diff --git a/fail-tests/fail.stdout-diff b/fail-tests/fail.stdout-diff
index c574866..b4fe31a 100644
--- a/fail-tests/fail.stdout-diff
+++ b/fail-tests/fail.stdout-diff
@@ -1,4 +1,4 @@
 --- /dev/null	2017-03-27 15:43:35.669436670 +0300
-+++ fail-tests/fail.stdout-actual	2017-03-28 17:16:53.366886919 +0300
++++ fail-tests/fail.stdout-actual	2017-03-28 17:27:11.462899536 +0300
 @@ -0,0 +1 @@
 +this is not empty output to make test fail
diff --git a/yarnutils/__init__.py b/yarnutils/__init__.py
index 9c3ef7c..0a5e0c4 100644
--- a/yarnutils/__init__.py
+++ b/yarnutils/__init__.py
@@ -16,3 +16,4 @@
 # =*= License: GPL-3+ =*=
 
 
+from .vars import Variables
diff --git a/yarnutils/vars.py b/yarnutils/vars.py
new file mode 100644
index 0000000..9404ffa
--- /dev/null
+++ b/yarnutils/vars.py
@@ -0,0 +1,47 @@
+# Copyright 2017  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import os
+import yaml
+
+
+class Variables(object):
+
+    _basename = 'vars.yaml'
+
+    def __init__(self, dirname):
+        self._filename = os.path.join(dirname, self._basename)
+        self._dict = self._load()
+
+    def _load(self):
+        if os.path.exists(self._filename):
+            with open(self._filename) as f:
+                return yaml.safe_load(f)
+        else:
+            return {}
+
+    def _save(self, values):
+        with open(self._filename, 'w') as f:
+            return yaml.safe_dump(values, stream=f)
+
+    def __getitem__(self, key):
+        return self._dict.get(key)
+
+    def __setitem__(self, key, value):
+        self._dict[key] = value
+        self._save(self._dict)
diff --git a/yarnutils/vars_tests.py b/yarnutils/vars_tests.py
new file mode 100644
index 0000000..a49903e
--- /dev/null
+++ b/yarnutils/vars_tests.py
@@ -0,0 +1,43 @@
+# Copyright 2017  Lars Wirzenius
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# =*= License: GPL-3+ =*=
+
+
+import shutil
+import tempfile
+import unittest
+
+import yarnutils
+
+
+class VariablesTests(unittest.TestCase):
+
+    def setUp(self):
+        self.tempdir = tempfile.mkdtemp()
+
+    def tearDown(self):
+        shutil.rmtree(self.tempdir)
+
+    def test_unset_variable_is_None(self):
+        vars = yarnutils.Variables(self.tempdir)
+        self.assertEqual(vars['foo'], None)
+
+    def test_set_value_is_persistent(self):
+        vars1 = yarnutils.Variables(self.tempdir)
+        vars1['foo'] = 'bar'
+        vars2 = yarnutils.Variables(self.tempdir)
+        self.assertEqual(vars1['foo'], vars2['foo'])
+        self.assertEqual(vars2['foo'], 'bar')
-- 
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