curds: Add a class for pickling and unpickling objects
This gives us a convenient way to handle saved data. We use the 'with' statment to handle any errors without crashing. Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>
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@ -1,12 +1,47 @@
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# Copyright 2019 (c) Anna Schumaker.
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import os
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import pickle
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import xdg.BaseDirectory
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__resource = "emmental"
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if os.environ.get("EMMENTAL_TESTING"):
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__resource = "emmental-testing"
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READ = 'rb'
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WRITE = 'wb'
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emmental_data = xdg.BaseDirectory.save_data_path(__resource)
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def data_file_path(filename):
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return os.path.join(emmental_data, filename)
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class DataFile:
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def __init__(self, path, mode):
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self.path = data_file_path(path)
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self.mode = mode
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self.file = None
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def __enter__(self):
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path = self.path
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if self.mode == WRITE:
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path = data_file_path(f".{os.path.basename(self.path)}.tmp")
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if self.mode == WRITE or os.path.exists(path):
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self.file = open(path, self.mode)
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return self
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def __exit__(self, exp_type, exp_value, traceback):
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if self.file:
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self.file.close()
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self.file = None
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if self.mode == WRITE:
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path = data_file_path(f".{os.path.basename(self.path)}.tmp")
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os.rename(path, self.path)
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return True
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def pickle(self, obj):
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if self.file:
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pickle.dump(obj, self.file, pickle.HIGHEST_PROTOCOL)
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def unpickle(self):
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if self.file:
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return pickle.load(self.file)
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@ -6,8 +6,14 @@ import xdg.BaseDirectory
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xdg_data_home = xdg.BaseDirectory.xdg_data_home
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testing_data = os.path.join(xdg_data_home, "emmental-testing")
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testing_file = os.path.join(testing_data, "test.file")
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testing_temp = os.path.join(testing_data, ".test.file.tmp")
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class TestDataModule(unittest.TestCase):
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def setUp(self):
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if os.path.exists(testing_file):
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os.remove(testing_file)
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def test_dir(self):
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self.assertEqual(data.emmental_data, testing_data)
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self.assertTrue(os.path.exists(testing_data))
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@ -17,3 +23,41 @@ class TestDataModule(unittest.TestCase):
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path = os.path.join(testing_data, "test")
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self.assertEqual(data.data_file_path("test"), path)
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self.assertFalse(os.path.exists(path))
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self.assertEqual(data.READ, 'rb')
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self.assertEqual(data.WRITE, 'wb')
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def test_data_file_init(self):
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f = data.DataFile("test.file", data.READ)
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self.assertEqual(f.path, testing_file)
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self.assertFalse(os.path.exists(testing_file))
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self.assertEqual(f.mode, data.READ)
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self.assertIsNone(f.file)
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f = data.DataFile("test.file", data.WRITE)
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self.assertFalse(os.path.exists(testing_file))
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self.assertEqual(f.mode, data.WRITE)
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self.assertIsNone(f.file)
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def test_data_file_read_write(self):
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test = [ "test", "saving", "a", "list" ]
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with data.DataFile("test.file", data.READ) as f:
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self.assertIsNone(f.file)
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f.pickle(test)
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self.assertIsNone(f.unpickle())
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with data.DataFile("test.file", data.WRITE) as f:
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self.assertIsNotNone(f.file)
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self.assertEqual(f.file.name, testing_temp)
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self.assertFalse(os.path.exists(testing_file))
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self.assertTrue(os.path.exists(testing_temp))
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f.pickle(test)
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self.assertIsNone(f.file)
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self.assertFalse(os.path.exists(testing_temp))
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self.assertTrue(os.path.exists(testing_file))
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with data.DataFile("test.file", data.READ) as f:
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self.assertIsNotNone(f.file)
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self.assertEqual(f.file.name, testing_file)
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lst = f.unpickle()
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self.assertEqual(test, lst)
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