Merge pull request #159 from jbasko/track-changes

Track changes

Author: jbasko

.bumpversion.cfg

@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 1.27.0
+current_version = 1.28.0
 commit = true
 tag = false
 

configmanager/__init__.py

@@ -1,4 +1,4 @@
-__version__ = '1.27.0'
+__version__ = '1.28.0'
 
 from .managers import Config
 from .items import Item

configmanager/items.py

@@ -144,9 +144,6 @@ def __repr__(self):
     def __str__(self):
         return repr(self)
 
-    def __eq__(self, other):
-        return isinstance(other, self.__class__) and self.__dict__ == other.__dict__
-
     @property
     def str_value(self):
         if self.raw_str_value is not not_set:

configmanager/managers.py

@@ -5,6 +5,36 @@
 from .sections import Section
 
 
+class _TrackingContext(object):
+    def __init__(self, config):
+        self.config = config
+        self.hook = None
+        self.changes = {}
+
+    def __enter__(self):
+        return self.push()
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.pop()
+
+    def _value_changed(self, item, old_value, new_value):
+        if old_value != new_value:
+            self.changes[item] = new_value
+
+    def push(self):
+        assert self.hook is None
+        self.hook = self.config.hooks.register_hook(self.config.hooks.item_value_changed, self._value_changed)
+        self.config._tracking_contexts.append(self)
+        return self
+
+    def pop(self):
+        popped = self.config._tracking_contexts.pop()
+        assert popped is self
+        self.config.hooks.unregister_hook(self.config.hooks.item_value_changed, self._value_changed)
+        self.hook = None
+        return self.changes
+
+
 class Config(Section):
     """
     Represents a configuration tree.
@@ -104,6 +134,8 @@ def __init__(self, schema=None, **configmanager_settings):
 
         super(Config, self).__init__()
 
+        self._tracking_contexts = []
+
         self._configparser_adapter = None
         self._json_adapter = None
         self._yaml_adapter = None
@@ -122,6 +154,9 @@ def __repr__(self):
     def settings(self):
         return self._settings
 
+    def tracking_context(self):
+        return _TrackingContext(self)
+
     @property
     def configparser(self):
         """

setup.py

@@ -26,7 +26,7 @@ def read(fname):
     description='Extensible, object-oriented manager of configuration items and configuration trees of arbitrary depth',
     long_description=read('README.rst'),
     packages=['configmanager'],
-    install_requires=['six==1.10.0', 'future==0.16.0', 'configparser==3.5.0', 'hookery<0.4.0'],
+    install_requires=['six==1.10.0', 'future==0.16.0', 'configparser==3.5.0', 'hookery==0.3.2'],
     extras_require={
         'yaml': ['PyYAML'],
         'click': ['click'],

tests/test_item.py

@@ -185,15 +185,27 @@ def test_can_set_int_value_to_none():
     assert c.value is None
 
 
-def test_equality():
+def test_different_items_are_unequal_even_when_state_matches():
+    # This is so that we can have items hashable.
+    # There is no need to compare two items. Compare values or other attributes, but the whole
+    # thing is just an illusion.
+
     c = Item('a', type=str, value=None)
     cc = Item('a', type=str, value=None)
-    assert c == cc
+    assert c != cc
 
     d = Item('a', type=int, value=None)
     assert c != d
 
 
+def test_items_are_hashable():
+    c = Item('a', type=str, value=None)
+    d = Item('a', type=str, value=None)
+
+    e = {c: 1, d: 2}
+    assert e == {c:1, d:2}
+
+
 def test_item_is_equal_to_itself():
     c = Item('a')
     assert c == c

tests/test_track_changes.py

@@ -0,0 +1,69 @@
+from configmanager import Config
+
+
+def test_tracking_context():
+    config = Config({
+        'greeting': 'Hello, world!',
+        'db': {
+            'user': 'root',
+        },
+    })
+
+    ctx1 = config.tracking_context()
+    ctx1.push()
+    ctx1.pop()
+
+    assert ctx1.changes == {}
+
+    with config.tracking_context() as ctx2:
+        pass
+
+    assert ctx2.changes == {}
+
+    assert ctx1.changes == {}
+    assert ctx1 is not ctx2
+
+    ctx3 = config.tracking_context()
+    ctx3.push()
+
+    config.greeting.value = 'Hey!'
+    assert ctx3.changes == {config.greeting: 'Hey!'}
+
+    ctx3.pop()
+    assert ctx3.changes == {config.greeting: 'Hey!'}
+
+    # ctx3 is no longer tracking changes
+    config.greeting.value = 'What is up!'
+    assert ctx3.changes == {config.greeting: 'Hey!'}
+
+    # neither are ctx1 and ctx2
+    assert ctx1.changes == {}
+    assert ctx2.changes == {}
+
+    # track in ctx3:
+    with ctx3:
+        config.db.user.value = 'admin'
+        assert ctx3.changes == {config.greeting: 'Hey!', config.db.user: 'admin'}
+    assert ctx3.changes == {config.greeting: 'Hey!', config.db.user: 'admin'}
+
+    # again, ctx3 is no longer tracking
+    config.db.user.value = 'Administrator'
+
+    assert ctx3.changes == {config.greeting: 'Hey!', config.db.user: 'admin'}
+
+    # neither are ctx1 and ctx2
+    assert ctx1.changes == {}
+    assert ctx2.changes == {}
+
+    # nested contexts
+
+    with ctx1:
+        config.db.user.value = 'user-in-ctx1'
+
+        with ctx2:
+            config.greeting.value = 'greeting-in-ctx2'
+
+        config.greeting.value = 'greeting-in-ctx1'
+
+    assert ctx1.changes == {config.db.user: 'user-in-ctx1', config.greeting: 'greeting-in-ctx1'}
+    assert ctx2.changes == {config.greeting: 'greeting-in-ctx2'}