Default params, wrapper functions and better call function

.gitignore

@@ -1,3 +1,6 @@
+# Editors
+.vscode
+
 # Python
 *.py[co]
 

AUTHORS

@@ -12,3 +12,4 @@ Patches and Suggestions
 - Eric Smith
 - Evan Klitzke
 - Thomas Hanssen Nornes
+- Michel Betancourt

README.rst

@@ -51,6 +51,75 @@ You can also predefine events for a single Events instance by passing an iterato
     # this will raise an EventsException as `on_change` is unknown to events:
     >>> events.on_change += something_changed
 
+You can define default arguments for events
+
+.. code-block:: pycon
+
+    >>> from events import Events
+    >>> class MyClass(object):
+    ...     def __init__(self):
+    ...         self.events = Events(default=[str(self) + ": "])
+    ...         self.events.on_change += print
+    ...     def __str__(self):
+    ...         return self.__class__.__name__
+    >>> inst = MyClass()
+    >>> inst.events.on_change("Hello world!")
+    >>> inst.events.on_change("Bye world!")
+
+You can also declare a global wrap function that allows to insert all the events a 
+use is at the time of debugging or avoiding the execution of an event under certain 
+circumstances
+
+.. code-block:: pycon
+
+    >>> from events import Events
+    >>> def debug(func, *args, **kwargs):
+    ...     logging.debug("Trigger event: " + func.__name__)
+    ...     func(*args, **kwargs)
+    >>> class MyClass(object):
+    ...     def __init__(self):
+    ...         self.events = Events(wrapper=debug)
+    ...         self.events.on_change += print
+    ...     def __str__(self):
+    ...         return self.__class__.__name__
+    >>> inst = MyClass()
+    >>> inst.events.on_change("Hello world!")
+    >>> inst.events.on_change("Bye world!")
+
+Do not worry about sending exact parameters or fill your functions with * args, * 
+kwargs the functions are only calls with the parameters they need
+
+.. code-block:: pycon
+
+    >>> from events import Events
+    >>> class MyClass(object):
+    ...     def __init__(self):
+    ...         self.events = Events(default=[self])
+    ...         self.events.on_change += self.destroy
+    ...         self.events.on_change += self.paint
+    ...     def destroy(self):
+    ...         pass
+    ...     def paint(self):
+    ...         pass
+    ...     def __str__(self):
+    ...         return self.__class__.__name__
+    >>> def need1(arg):
+    ...    print(f"need1 {arg}")
+    >>> def need2(arg, arg2):
+    ...    print(f"need2 {arg} {arg2}")
+    >>> def need3(arg, arg3, named):
+    ...    print(f"need3 {arg} {arg3} {named}")
+    >>> def function(sender):
+    ...    print(sender)
+    ...    sender.paint()
+    >>> my_class = MyClass()
+    >>> my_class.events.on_change()
+    >>> my_class.events.on_change += function
+    >>> my_class.events.on_change()
+    >>> my_class.events.on_key += need1
+    >>> my_class.events.on_key += need2
+    >>> my_class.events.on_key += need3
+    >>> my_class.events.on_key('arg', 'arg2', arg3='arg3', named='named')
 
 Documentation
 -------------

events/__init__.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 from .events import Events, EventsException
 
-__version__ = '0.3' # test
+__version__ = '0.4.1' # test
 
 __all__ = [
     Events.__name__,

events/events.py

@@ -12,7 +12,7 @@
     :copyright: (c) 2014-2017 by Nicola Iarocci.
     :license: BSD, see LICENSE for more details.
 """
-
+from inspect import signature
 
 class EventsException(Exception):
     pass
@@ -35,8 +35,13 @@ class Events:
 
             xxx.OnChange = event('OnChange')
     """
-    def __init__(self, events=None):
-
+    def __init__(self, events=None, default=None, wrapper=None):
+        if not isinstance(default, (list, tuple)) and default is not None:
+            raise AttributeError("type object %s is not list" % (type(default)))
+        elif not callable(wrapper) and wrapper is not None:
+            raise AttributeError("type object %s is not function" % (type(wrapper)))
+        self._wrapper = wrapper
+        self._default = default
         if events is not None:
 
             try:
@@ -61,7 +66,7 @@ def __getattr__(self, name):
             if name not in self.__class__.__events__:
                 raise EventsException("Event '%s' is not declared" % name)
 
-        self.__dict__[name] = ev = _EventSlot(name)
+        self.__dict__[name] = ev = _EventSlot(name, self._default, self._wrapper)
         return ev
 
     def __repr__(self):
@@ -72,35 +77,46 @@ def __repr__(self):
     __str__ = __repr__
 
     def __len__(self):
-        return len(self.__dict__.items())
+        return len([x for x in self.__dict__ if not x.startswith('_')])
 
     def __iter__(self):
         def gen(dictitems=self.__dict__.items()):
-            for attr, val in dictitems:
+            for _, val in dictitems:
                 if isinstance(val, _EventSlot):
                     yield val
         return gen()
 
 
 class _EventSlot:
-    def __init__(self, name):
+    def __init__(self, name, default=None, wrapper=None):
+        self._default = default or []
+        self._wrapper = wrapper or (lambda func, *args, **kwargs: func(*args, **kwargs))
         self.targets = []
         self.__name__ = name
 
     def __repr__(self):
         return "event '%s'" % self.__name__
 
-    def __call__(self, *a, **kw):
-        for f in tuple(self.targets):
-            f(*a, **kw)
-
-    def __iadd__(self, f):
-        self.targets.append(f)
+    def __call__(self, *args, **kwargs):
+        for function in tuple(self.targets):
+            ckwargs = kwargs.copy()
+            cargs = self._default + list(args)
+            params = signature(function).parameters
+            if not any(map(lambda x: x.kind == x.VAR_KEYWORD, params.values())):
+                for key in kwargs:
+                    if not key in params:
+                        del ckwargs[key]
+            if not any(map(lambda x: x.kind == x.VAR_POSITIONAL, params.values())):
+                cargs = cargs[:len(params)-len(ckwargs)]
+            self._wrapper(function, *cargs, **ckwargs)
+
+    def __iadd__(self, function):
+        self.targets.append(function)
         return self
 
-    def __isub__(self, f):
-        while f in self.targets:
-            self.targets.remove(f)
+    def __isub__(self, function):
+        while function in self.targets:
+            self.targets.remove(function)
         return self
 
     def __len__(self):

events/tests/tests.py

@@ -18,6 +18,9 @@ def callback2(self):
     def callback3(self):
         pass
 
+    def callback4(self, arg1, arg2):
+        self.assertEqual(arg1, "Default_1")
+        self.assertEqual(arg2, "Default_2")
 
 class TestEvents(TestBase):
     def test_getattr(self):
@@ -101,6 +104,10 @@ def test_isub(self):
 
 
 class TestInstanceEvents(TestBase):
+    def test_instance_default(self):
+        events = Events(default=["Default_1", "Default_2"])
+        events.on_event += self.callback4
+        events.on_event()
 
     def test_getattr(self):