added Closeable, v2.14.2

CHANGELOG.md

 # v2.14.2
 
 * satella futures are now generic
-
+* added `Closeable`

docs/coding/structures.rst

@@ -324,3 +324,8 @@ Subqueue
 .. autoclass:: satella.coding.structures.Subqueue
     :members:
 
+Closeable
+---------
+
+.. autoclass:: satella.coding.Closeable
+    :members:

satella/__init__.py

-__version__ = '2.14.2_a2'
+__version__ = '2.14.2'

satella/coding/__init__.py

@@ -14,7 +14,7 @@ from .metaclasses import metaclass_maker, wrap_with, dont_wrap, wrap_property, D
     CopyDocsFrom
 from .misc import update_if_not_none, update_key_if_none, update_attr_if_none, queue_iterator, \
     update_key_if_not_none, source_to_function, update_key_if_true, \
-    get_arguments, call_with_arguments, chain_callables
+    get_arguments, call_with_arguments, chain_callables, Closeable
 from .overloading import overload, class_or_instancemethod
 from .recast_exceptions import rethrow_as, silence_excs, catch_exception, log_exceptions, \
     raises_exception

satella/coding/misc.py

@@ -6,6 +6,52 @@ from queue import Queue
 from satella.coding.recast_exceptions import rethrow_as
 
 
+class Closeable:
+    """
+    A class that needs to clean up it's own resources.
+
+    It's destructor calls .close(). Use like this:
+
+    >>> class MyClose(Closeable):
+    >>>     def close(self):
+    >>>         if super().close():
+    >>>             .. clean up ..
+
+    Can be also used as a context manager, with close() called upon __exit__.
+
+    You should extend both __init__ and close()
+    """
+    def __init__(self):
+        self.__finalized = False
+
+    def close(self) -> bool:
+        """
+        Check if the resource needs cleanup, and clean up this resource.
+
+        Use like this:
+
+        >>> class MyClose(Closeable):
+        >>>     def close(self):
+        >>>         if super().close():
+        >>>             .. clean up ..
+
+        :return: whether the cleanup should proceed
+        """
+        try:
+            return not self.__finalized
+        finally:
+            self.__finalized = True
+
+    def __del__(self) -> None:
+        self.close()
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.close()
+
+
 def queue_iterator(queue: Queue) -> tp.Iterator:
     """
     Syntactic sugar for

tests/test_coding/test_misc.py

+import gc
 import unittest
 
 from satella.coding import update_key_if_not_none, overload, class_or_instancemethod, \
-    update_key_if_true, get_arguments, call_with_arguments, chain_callables
+    update_key_if_true, get_arguments, call_with_arguments, chain_callables, Closeable
 from satella.coding.structures import HashableMixin
 from satella.coding.transforms import jsonify, intify
 
 
 class TestCase(unittest.TestCase):
 
+    def test_closeable(self):
+        a = {'test': False}
+
+        class MyClose(Closeable):
+            def close(self):
+                if super().close():
+                    a['test'] = True
+
+        b = MyClose()
+        del b
+        gc.collect()
+        self.assertTrue(a['test'])
+
     def test_chain_callables(self):
         def a():
             return 5