versionary: add get_applicable method

which adds the possibility to select a version based on passed
minium and maximum versions requirements,
so we do not need to know what versions are actually implemented and
can select the highest available version within the given boundaries.

If no version was found a new exception NoApplicableVersion is raised

Signed-off-by: Konrad Weihmann <[email protected]>

CONTRIBUTORS.md

@@ -11,3 +11,5 @@ Keep the list in alfabetical order please.
 
  * Devhouse Spindle {[email protected]}
  * Marco Vellinga {[email protected]}
+ * Konrad Weihmann {[email protected]}
+

tests/test_decorator.py

@@ -1,7 +1,7 @@
 from pytest import raises
 
 from versionary.decorators import versioned
-from versionary.exceptions import DuplicateVersionException, InheritanceException, InvalidVersionException
+from versionary.exceptions import DuplicateVersionException, InheritanceException, InvalidVersionException, NoApplicableVersion
 
 from .utils.mixed_members import MixedClass, mixed_func
 from .utils.versioned_members import MyClass, MyInheritanceClass, my_function, your_function
@@ -24,6 +24,17 @@ def test_decorator_for_classes_without_number():
     assert MyClass.v2().hello() == 4
 
 
+def test_decorator_for_classes_get_applicable():
+    """
+    Test the decorator for classes via get_applicable.
+    """
+    assert MyClass.get_applicable()().hello() == 4
+    assert MyClass.get_applicable(minver=2)().hello() == 4
+    assert MyClass.get_applicable(maxver=1)().hello() == 3
+    with raises(NoApplicableVersion):
+        MyClass.get_applicable(minver=100)().hello()
+
+
 def test_decorator_for_class_inheritance_without_number():
     """
     Test the decorator for classes that inherit without a number.

tests/test_utils.py

@@ -29,7 +29,7 @@ def test_create_proxy_class():
     """
     base_name = 'base_name'
 
-    proxy = create_proxy_class(base_name)
+    proxy = create_proxy_class(base_name, 123)
 
     message = 'Cannot call `base_name` directly, use versioned attributes instead (`base_name`.vX)'
 

versionary/decorators.py

@@ -116,7 +116,7 @@ def wrap(member):
             validate_inheritance_for_class(member)
 
         # Get or create the proxy class to return.
-        proxy = version_members.get('proxy', create_proxy_class(name))
+        proxy = version_members.get('proxy', create_proxy_class(name, module))
 
         # Add new version method to this proxy class.
         setattr(proxy, '%s%s' % (PROXY_VERSION_TAG, version), staticmethod(member))

versionary/exceptions.py

@@ -41,3 +41,10 @@ class NotCallableException(Exception):
     Raised when trying to call the ProxyClass which shouldn't be called.
     """
     pass
+
+
+class NoApplicableVersion(Exception):
+    """
+    Raised when no version matching the criteria was found.
+    """
+    pass

versionary/utils.py

@@ -4,7 +4,7 @@
 
 from six import with_metaclass
 
-from .exceptions import InvalidVersionException, NotCallableException
+from .exceptions import InvalidVersionException, NotCallableException, NoApplicableVersion
 
 CLASS, FUNCTION = 0, 1
 CLASS_VERSION_TAG = 'V'
@@ -37,7 +37,7 @@ def determine_member_type(member):
     return member_type
 
 
-def create_proxy_class(base_name):
+def create_proxy_class(base_name, mod):
     """
     Function to create a proxy class to be able to set attributes to.
     This is used to make my_func.v1() or MyClass.v1() possible.
@@ -83,7 +83,17 @@ def __getattr__(cls, name):
             raise AttributeError('%r has no attribute %r' %
                                  (cls._base_name, name))
 
+        def get_applicable(cls, minver=0, maxver=10e9):
+            version_table = getattr(cls._modref, '__version_table__')
+            try:
+                best_version = max([x for x in version_table[cls._base_name]
+                                   ['members'].keys() if x <= maxver and x >= minver])
+                return version_table[cls._base_name]['members'][best_version]
+            except ValueError:
+                raise NoApplicableVersion()
+
     setattr(ProxyType, '_base_name', base_name)
+    setattr(ProxyType, '_modref', mod)
 
     class ProxyClass(with_metaclass(ProxyType)):
         """