import inspect
from pkg_resources import iter_entry_points
from tw.core.util import pre_post_hooks
from tw.core.exceptions import *
__all__ = [ "WidgetType", "WidgetsList"]
class WidgetType(type):
def __new__(meta,name,bases,dct):
dct['_cls_children'] = dct.pop('children',_children_from_bases(bases))
if isinstance(dct.get('params'), dict):
for param_name, doc in dct['params'].iteritems():
dct[param_name+'__doc'] = doc
params = frozenset_from_all_bases(dct,bases,'params')
frozenset_from_all_bases(dct,bases,'source_vars')
__init__ = dct.pop('__init__', None)
if __init__:
dct['__init__'] = pre_post_hooks(None, 'post_init')(__init__)
new = type.__new__(meta,name,bases,dct)
return new
@classmethod
def iter_classes(meta):
"""Iterates over all the Widget subclasses in the modules
that are declared as `toscawidgets.widgets` entrypoints
>>> from tw.api import Widget
>>> len(list(Widget.iter_classes())) > 0
True
"""
seen = set()
for ep in iter_entry_points('toscawidgets.widgets'):
try:
mod = ep.load(False)
except ImportError, e:
continue
for name in dir(mod):
obj = getattr(mod, name)
if isinstance(obj, meta) and obj not in seen:
seen.add(obj)
yield obj
def _children_from_bases(bases):
for base in bases:
if hasattr(base, '_cls_children'):
return base._cls_children
return []
def frozenset_from_all_bases(clsdct, bases, name):
_set = set(clsdct.pop(name,[]))
[_set.update(getattr(b,name)) for b in bases if hasattr(b, name)]
fs = clsdct[name] = frozenset(_set)
return fs
class WidgetsListType(type):
def __new__(meta,name,bases,dct):
clones = []
for id, w in dct.items():
if hasattr(w,'_serial') and hasattr(w, 'clone'):
dct.pop(id)
clones.append((w._serial, id, w.clone) )
clones.sort()
def __init__(self, clones=clones):
# we instantiate the clones on initialization
widgets = [w[2](id=w[1]) for w in clones]
self.extend(widgets)
dct.update({'__slots__':[], '__init__':__init__})
return type.__new__(meta,name,bases,dct)
def __add__(self, other):
if isinstance(self, list) and isinstance(other,list):
return list.__add__(self,other)
elif isinstance(self, list) and inspect.isclass(other):
return list.__add__(self,other())
elif inspect.isclass(self) and isinstance(other,list):
return list.__add__(self(),other)
elif inspect.isclass(self) and inspect.isclass(other):
return list.__add__(self(),other())
def __radd__(self, other):
if isinstance(self, list) and isinstance(other,list):
return list.__add__(other,self)
elif isinstance(self, list) and inspect.isclass(other):
return list.__add__(other(),self)
elif inspect.isclass(self) and isinstance(other,list):
return list.__add__(other,self())
elif inspect.isclass(self) and inspect.isclass(other):
return list.__add__(other(),self())
class WidgetsList(list):
"""
Syntactic sugar for declaring a list of widgets.
>>> from tw.api import Widget
>>> class Widgets(WidgetsList):
... a = Widget()
... b = Widget()
... c = Widget()
...
>>> widgets = Widgets()
>>> [w.id for w in widgets]
['a', 'b', 'c']
WidgetsLists can be passed to another widget as children by
the instance or the class.
>>> w = Widget('foo', children=widgets)
>>> [c.id for c in w.children]
['foo_a', 'foo_b', 'foo_c']
>>> w = Widget('foo', children=Widgets)
>>> [c.id for c in w.children]
['foo_a', 'foo_b', 'foo_c']
WidgetsLists subclasses can also be added to reuse common widgets
>>> class Widgets2(WidgetsList):
... d = Widget()
...
>>> widgets = Widgets + Widgets2
>>> [w.id for w in widgets]
['a', 'b', 'c', 'd']
>>> widgets = Widgets2 + Widgets
>>> [w.id for w in widgets]
['d', 'a', 'b', 'c']
"""
__metaclass__ = WidgetsListType
if __name__ == "__main__":
import doctest
doctest.testmod()