diff --git a/CHANGELOG.md b/CHANGELOG.md
index e048783a204866246ff68e054efdadb395b847b1..e069212ae9f12b3cea5e9b5b4bd51906bf42c85d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,5 @@
-# v2.21.4
+# v2.22.0rc1
* moar tests for CPManager
-* added tainting
\ No newline at end of file
+* added tainting
+* added Environments
\ No newline at end of file
diff --git a/docs/coding/environment.rst b/docs/coding/environment.rst
new file mode 100644
index 0000000000000000000000000000000000000000..46fe521079a5f2c7e9a14ed00d1506fc9672bed6
--- /dev/null
+++ b/docs/coding/environment.rst
@@ -0,0 +1,21 @@
+Sometimes, you have a bunch of arguments to functions
+such as the database connection object, and would
+prefer them not to be passed by an argument, but configured
+through Satella's Environments themselves:
+
+.. autoclass:: satella.coding.Context
+ :members:
+
+You can think of them as a stack of cards each carrying a set of variable names. The variable, if not present
+on the current card, will be checked upwards for parent of this card. Each thread, by default, gets a
+separate hierarchy. Removing a variable on one card will not affect it's parent, however the variable will remain
+inaccessible for the duration of this context. Use them like this:
+
+.. code-block:: python
+
+ with Context() as ctxt:
+ ctxt.value = 55
+ with Context() as new_ctxt:
+ new_ctxt.value = 66
+ assert ctxt.value == 66
+ assert ctxt.value == 55
diff --git a/docs/index.rst b/docs/index.rst
index 2ffd07412087b8384ad899c24d8bcfb46e6f50f0..1baf94281037b357ac2541a3ffacb8825a5f1b72 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -13,6 +13,7 @@ Visit the project's page at GitHub_!
configuration/schema
configuration/sources
coding/ctxt_managers
+ coding/environment
coding/functions
coding/futures
coding/structures
diff --git a/satella/__init__.py b/satella/__init__.py
index 68faeb8bf0bc18a23e81f9b28c929371d2c42b51..9015163e78de0fadeee4903d6861cdef1a2e1f84 100644
--- a/satella/__init__.py
+++ b/satella/__init__.py
@@ -1 +1 @@
-__version__ = '2.21.4a2'
+__version__ = '2.22.0rc2'
diff --git a/satella/coding/__init__.py b/satella/coding/__init__.py
index b8963fa4d7c99dd537db82e6d03f5a7db76d3aca..612957d321d6b21dc52a7360b7a4219211612f49 100644
--- a/satella/coding/__init__.py
+++ b/satella/coding/__init__.py
@@ -17,6 +17,7 @@ from .misc import update_if_not_none, update_key_if_none, update_attr_if_none, q
update_key_if_not_none, source_to_function, update_key_if_true, \
get_arguments, call_with_arguments, chain_callables, Closeable, contains, \
enum_value
+from .environment import Context
from .overloading import overload, class_or_instancemethod
from .recast_exceptions import rethrow_as, silence_excs, catch_exception, log_exceptions, \
raises_exception, reraise_as
@@ -24,7 +25,7 @@ from .expect_exception import expect_exception
from .deep_compare import assert_equal, InequalityReason, Inequal
__all__ = [
- 'EmptyContextManager',
+ 'EmptyContextManager', 'Context',
'assert_equal', 'InequalityReason', 'Inequal',
'Closeable', 'contains', 'enum_value', 'reraise_as',
'expect_exception',
diff --git a/satella/coding/environment.py b/satella/coding/environment.py
new file mode 100644
index 0000000000000000000000000000000000000000..c0482a1d344dcc9156e5ec8f4309b61ad45cc906
--- /dev/null
+++ b/satella/coding/environment.py
@@ -0,0 +1,105 @@
+from __future__ import annotations
+import typing as tp
+import threading
+from satella.coding.typing import V
+
+from .misc import Closeable
+
+
+local = threading.local()
+
+
+THEY_HATIN = object()
+
+
+class Context:
+ """
+ New layer of environment. Can have it's own variables, or can hoist them onto the parent.
+ """
+
+ def __init__(self, parent: tp.Optional[Context] = None, **variables):
+ self.parent = parent
+ self.variables = {}
+ self.bool = None
+
+ def __str__(self):
+ return str(id(self))
+
+ def push_up(self, item: str) -> None:
+ """
+ Advance current variable to the top of the card stack.
+
+ :param item: variable name
+ """
+ var = self.variables.pop(item)
+ self.parent.variables[item] = var
+
+ def __getattr__(self, item: str):
+ if item in self.variables:
+ v = self.variables[item]
+ if v is not THEY_HATIN:
+ return v
+ raise AttributeError()
+ if self.parent is not None:
+ return getattr(self.parent, item)
+ raise AttributeError()
+
+ def __enter__(self):
+ global local
+ try:
+ parent = local.thread_context
+ except AttributeError:
+ parent = None
+ ctxt = Context(parent=parent)
+ if ctxt is not parent:
+ ctxt.parent = parent
+ local.thread_context = ctxt
+ return ctxt
+
+ def __setattr__(self, key: str, value: V):
+ """
+ Set a value
+ """
+ if key in ('parent', 'variables', 'bool'):
+ return super().__setattr__(key, value)
+ else:
+ self.variables[key] = value
+
+ def __delattr__(self, item: str) -> None:
+ self.variables[item] = THEY_HATIN
+
+ def does_exist(self, val: str) -> bool:
+ """
+ Does a given value exist on stack for this call of function?
+ """
+ if val in self.variables:
+ if self.variables[val] is THEY_HATIN:
+ return False
+ return True
+ else:
+ if self.parent is None:
+ return False
+ return self.parent.does_exist(val)
+
+ def __exit__(self, exc_type, exc_val, exc_tb) -> bool:
+ if self.parent is None:
+ try:
+ del local.thread_context
+ except AttributeError:
+ pass
+ else:
+ local.thread_context = self.parent
+ return False
+
+ @staticmethod
+ def get() -> Context:
+ """
+ Return a local context for this thread
+ """
+ global local
+ try:
+ return local.thread_context
+ except AttributeError:
+ ctxt = Context()
+ local.thread_context = ctxt
+ return ctxt
diff --git a/satella/debug/test_environment.py b/satella/debug/test_environment.py
new file mode 100644
index 0000000000000000000000000000000000000000..c6c743466e18bd7ce4d306feae5037c495b997c3
--- /dev/null
+++ b/satella/debug/test_environment.py
@@ -0,0 +1,31 @@
+import unittest
+
+from satella.coding.environment import Context
+
+
+class TestEnvs(unittest.TestCase):
+
+ def test_envs(self):
+ ctxt = Context.get()
+ ctxt.value = 5
+ self.assertEqual(ctxt.value, 5)
+ with Context() as new_ctxt:
+ self.assertEqual(new_ctxt.value, 5)
+
+ def test_delete_envs(self):
+ ctxt = Context.get()
+ ctxt.value = 5
+ self.assertEqual(ctxt.value, 5)
+ with Context() as new_ctxt:
+ del new_ctxt.value
+ self.assertRaises(AttributeError, lambda: new_ctxt.value)
+ self.assertEqual(ctxt.value, 5)
+
+ def test_nesting(self):
+ with Context() as ctxt:
+ ctxt.value = 55
+ with Context() as new_ctxt:
+ new_ctxt.value = 66
+ assert new_ctxt.value == 66
+ assert ctxt.value == 55
+