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""" Context adapter for Python instances. """
# Standard library imports.
import re
# Enthought library imports.
from apptools.naming.api import Binding, ContextAdapter
from apptools.naming.api import OperationNotSupportedError, naming_manager
from traits.api import HasTraits, List, Property, Str
class InstanceContextAdapter(ContextAdapter):
""" Context adapter for Python instances. """
#### 'Context' interface ##################################################
# The name of the context within its own namespace.
namespace_name = Property(Str)
#### 'InstanceContextAdapter' interface ###################################
# By default every public attribute of an instance is exposed. Use the
# following traits to either include or exclude attributes as appropriate.
#
# Regular expressions that describe the names of attributes to include.
include = List(Str)
# Regular expressions that describe the names of attributes to exclude. By
# default we exclude 'protected' and 'private' attributes and any
# attributes that are artifacts of the traits mechanism.
exclude = List(Str, ['_', 'trait_'])
###########################################################################
# 'Context' interface.
###########################################################################
#### Properties ###########################################################
def _get_namespace_name(self):
""" Returns the name of the context within its own namespace. """
base = self.context.namespace_name
if len(base) > 0:
base += '/'
names = self.context.search(self.adaptee)
return base + names[0]
###########################################################################
# Protected 'Context' interface.
###########################################################################
def _is_bound(self, name):
""" Is a name bound in this context? """
return name in self._list_names()
def _lookup(self, name):
""" Looks up a name in this context. """
obj = getattr(self.adaptee, name)
return naming_manager.get_object_instance(obj, name, self)
def _lookup_binding(self, name):
""" Looks up the binding for a name in this context. """
return Binding(name=name, obj=self._lookup(name), context=self)
def _bind(self, name, obj):
""" Binds a name to an object in this context. """
state = naming_manager.get_state_to_bind(obj, name, self)
setattr(self.adaptee, name, state)
return
def _rebind(self, name, obj):
""" Rebinds a name to an object in this context. """
self._bind(name, obj)
return
def _unbind(self, name):
""" Unbinds a name from this context. """
delattr(self.adaptee, name)
return
def _rename(self, old_name, new_name):
""" Renames an object in this context. """
# Bind the new name.
setattr(self.adaptee, new_name, self._lookup(old_name))
# Unbind the old one.
delattr(self.adaptee, old_name)
return
def _create_subcontext(self, name):
""" Creates a sub-context of this context. """
raise OperationNotSupportedError()
def _destroy_subcontext(self, name):
""" Destroys a sub-context of this context. """
raise OperationNotSupportedError()
def _list_bindings(self):
""" Lists the bindings in this context. """
bindings = []
for name in self._list_names():
try:
obj = self._lookup(name)
bindings.append(Binding(name=name, obj=obj, context=self))
# We get attribute errors when we try to look up Event traits (they
# are write-only).
except AttributeError:
pass
return bindings
def _list_names(self):
""" Lists the names bound in this context. """
return self._get_public_attribute_names(self.adaptee)
###########################################################################
# Private interface.
###########################################################################
def _get_public_attribute_names(self, obj):
""" Returns the names of an object's public attributes. """
if isinstance(obj, HasTraits):
names = obj.trait_names()
elif hasattr(obj, '__dict__'):
names = self.adaptee.__dict__.keys()
else:
names = []
return [name for name in names if self._is_exposed(name)]
def _is_exposed(self, name):
""" Returns True iff a name should be exposed. """
if len(self.include) > 0:
is_exposed = self._matches(self.include, name)
elif len(self.exclude) > 0:
is_exposed = not self._matches(self.exclude, name)
else:
is_exposed = True
return is_exposed
def _matches(self, expressions, name):
""" Returns True iff a name matches any of a list of expressions. """
for expression in expressions:
if re.match(expression, name) is not None:
matches = True
break
else:
matches = False
return matches
#### EOF ######################################################################
|
