Performance optimisations, bumped to 1.0.2

Cached property no longer works like @Property, cannot have a setter.

tests/watson/common/test_decorators.py

@@ -14,5 +14,6 @@ def expensive_prop(self):
 
         c = MyClass()
         assert c.expensive_prop == 'This is an expensive call'
-        del c.expensive_prop
+        assert hasattr(c, '_expensive_prop')
+        del c._expensive_prop
         assert not hasattr(c, '_expensive_prop')

tests/watson/common/test_imports.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from pytest import raises
 from watson.common import imports
 from tests.watson.common.support import some_func
 
@@ -17,5 +18,5 @@ def test_load_definition_from_string(self):
         assert isinstance(data, dict)
 
     def test_load_invalid_definition(self):
-        assert None == imports.load_definition_from_string(
-            'invalid.module.Class')
+        with raises(ImportError):
+            imports.load_definition_from_string('invalid.module.Class')

watson/common/__init__.py

@@ -1,2 +1,2 @@
 # -*- coding: utf-8 -*-
-__version__ = '1.0.1'
+__version__ = '1.0.2'

watson/common/datastructures.py

@@ -80,6 +80,11 @@ class MultiDict(dict):
         print(multi_dict)  # {'one': [1, 'itchi']}
     """
 
+    def __init__(self, args=None):
+        items = args.items() if isinstance(args, dict) else args or ()
+        for key, value in items:
+            self.set(key, value)
+
     def set(self, key, value, replace=False):
         """Add a new item to the dictionary.
 
@@ -113,6 +118,9 @@ def __setitem__(self, key, value, replace=False):
                 value = existing
         dict.__setitem__(self, key, value)
 
+    def __getitem__(self, key, default=None):
+        return self.get(key, default)
+
     def update(self, a_dict):
         for key, value in a_dict.items():
             self[key] = value

watson/common/decorators.py

@@ -1,11 +1,11 @@
 # -*- coding: utf-8 -*-
-from functools import update_wrapper
-
-
-def cached_property(func):
+class cached_property(object):
 
     """Allows expensive property calls to be cached.
 
+    Once the property is called, it's result is stored in the corresponding
+    property name prefixed with an underscore.
+
     Example:
 
     .. code-block:: python
@@ -18,20 +18,16 @@ def expensive_call(self):
         klass = MyClass()
         klass.expensive_call  # initial call is made
         klass.expensive_call  # return value is retrieved from an internal cache
+        del klass._expensive_call
     """
-    prop = '_{name}'.format(name=func.__name__)
-
-    def _get_property(self):
-        try:
-            value = getattr(self, prop)
-        except AttributeError:
-            value = func(self)
-            setattr(self, prop, value)
-        return value
-
-    update_wrapper(_get_property, func)
 
-    def _del_property(self):
-        delattr(self, prop)
+    def __init__(self, func):
+        self.__name__ = func.__name__
+        self.__doc__ = func.__doc__
+        self.key = '_{name}'.format(name=self.__name__)
+        self.func = func
 
-    return property(_get_property, None, _del_property)
+    def __get__(self, obj, type=None):
+        if self.key not in obj.__dict__:
+            obj.__dict__[self.key] = self.func(obj)
+        return obj.__dict__[self.key]

watson/common/imports.py

@@ -2,7 +2,10 @@
 from importlib import import_module
 
 
-def load_definition_from_string(qualified_module):
+definition_lookup = {}
+
+
+def load_definition_from_string(qualified_module, cache=True):
     """Load a definition based on a fully qualified string.
 
     Returns:
@@ -15,13 +18,16 @@ def load_definition_from_string(qualified_module):
         definition = load_definition_from_string('watson.http.messages.Request')
         request = definition()
     """
+    if qualified_module in definition_lookup and cache:
+        return definition_lookup[qualified_module]
     parts = qualified_module.split('.')
     try:
         module = import_module('.'.join(parts[:-1]))
         obj = getattr(module, parts[-1:][0])
+        definition_lookup[qualified_module] = obj
         return obj
     except ImportError:
-        return None
+        raise
 
 
 def get_qualified_name(obj):