def create_subcontext(self, name):
""" Creates a sub-context. """
if len(name) == 0:
raise InvalidNameError('empty name')
# Parse the name.
components = self._parse_name(name)
# If there is exactly one component in the name then the operation
# takes place in this context.
if len(components) == 1:
atom = components[0]
# Is the name already bound?
if self._is_bound(atom):
raise NameAlreadyBoundError(name)
# Do the actual creation of the sub-context.
sub = self._create_subcontext(atom)
# Trait event notification.
self.object_added = NamingEvent(
new_binding=Binding(name=name, obj=sub, context=self))
# Otherwise, attempt to continue resolution into the next context.
else:
if not self._is_bound(components[0]):
raise NameNotFoundError(components[0])
next_context = self._get_next_context(components[0])
sub = next_context.create_subcontext('/'.join(components[1:]))
return sub
def lookup_binding(self, name):
""" Looks up the binding for a name relative to this context. """
if len(name) == 0:
raise InvalidNameError('empty name')
# Parse the name.
components = self._parse_name(name)
# If there is exactly one component in the name then the operation
# takes place in this context.
if len(components) == 1:
atom = components[0]
if not self._is_bound(atom):
raise NameNotFoundError(name)
# Do the actual lookup.
binding = self._lookup_binding(atom)
# Otherwise, attempt to continue resolution into the next context.
else:
if not self._is_bound(components[0]):
raise NameNotFoundError(components[0])
next_context = self._get_next_context(components[0])
binding = next_context.lookup_binding('/'.join(components[1:]))
return binding
def rename(self, old_name, new_name):
""" Binds a new name to an object. """
if len(old_name) == 0 or len(new_name) == 0:
raise InvalidNameError('empty name')
# Parse the names.
old_components = self._parse_name(old_name)
new_components = self._parse_name(new_name)
# If there is axactly one component in BOTH names then the operation
# takes place ENTIRELY in this context.
if len(old_components) == 1 and len(new_components) == 1:
# Is the old name actually bound?
if not self._is_bound(old_name):
raise NameNotFoundError(old_name)
# Is the new name already bound?
if self._is_bound(new_name):
raise NameAlreadyBoundError(new_name)
# Do the actual rename.
self._rename(old_name, new_name)
# Lookup the object that we are renaming to use in the event
# notification.
obj = self._lookup(new_name)
# Trait event notification.
self.object_renamed = NamingEvent(
old_binding=Binding(name=old_name, obj=obj, context=self),
new_binding=Binding(name=new_name, obj=obj, context=self))
else:
# fixme: This really needs to be transactional in case the bind
# succeeds but the unbind fails. To be safe should we just not
# support cross-context renaming for now?!?!
#
# Lookup the object.
obj = self.lookup(old_name)
# Bind the new name.
self.bind(new_name, obj)
# Unbind the old one.
self.unbind(old_name)
return
def bind(self, name, obj, make_contexts=False):
""" Binds a name to an object.
If 'make_contexts' is True then any missing intermediate contexts are
created automatically.
"""
if len(name) == 0:
raise InvalidNameError('empty name')
# Parse the name.
components = self._parse_name(name)
# If there is exactly one component in the name then the operation
# takes place in this context.
if len(components) == 1:
atom = components[0]
# Is the name already bound?
if self._is_bound(atom):
raise NameAlreadyBoundError(name)
# Do the actual bind.
self._bind(atom, obj)
# Trait event notification.
self.object_added = NamingEvent(
new_binding=Binding(name=name, obj=obj, context=self))
# Otherwise, attempt to continue resolution into the next context.
else:
if not self._is_bound(components[0]):
if make_contexts:
self._create_subcontext(components[0])
else:
raise NameNotFoundError(components[0])
next_context = self._get_next_context(components[0])
next_context.bind('/'.join(components[1:]), obj, make_contexts)
return
def rebind(self, name, obj, make_contexts=False):
""" Binds an object to a name that may already be bound.
If 'make_contexts' is True then any missing intermediate contexts are
created automatically.
The object may be a different object but may also be the same object
that is already bound to the specified name. The name may or may not be
already used. Think of this as a safer version of 'bind' since this
one will never raise an exception regarding a name being used.
"""
if len(name) == 0:
raise InvalidNameError('empty name')
# Parse the name.
components = self._parse_name(name)
# If there is exactly one component in the name then the operation
# takes place in this context.
if len(components) == 1:
# Do the actual rebind.
self._rebind(components[0], obj)
# Trait event notification.
self.object_changed = NamingEvent(
new_binding=Binding(name=name, obj=obj, context=self))
# Otherwise, attempt to continue resolution into the next context.
else:
if not self._is_bound(components[0]):
if make_contexts:
self._create_subcontext(components[0])
else:
raise NameNotFoundError(components[0])
next_context = self._get_next_context(components[0])
next_context.rebind('/'.join(components[1:]), obj, make_contexts)
return
def destroy_subcontext(self, name):
""" Destroys a sub-context. """
if len(name) == 0:
raise InvalidNameError('empty name')
# Parse the name.
components = self._parse_name(name)
# If there is exactly one component in the name then the operation
# takes place in this context.
if len(components) == 1:
atom = components[0]
if not self._is_bound(atom):
raise NameNotFoundError(name)
obj = self._lookup(atom)
if not self._is_context(atom):
raise NotContextError(name)
# Do the actual destruction of the sub-context.
self._destroy_subcontext(atom)
# Trait event notification.
self.object_removed = NamingEvent(
old_binding=Binding(name=name, obj=obj, context=self))
# Otherwise, attempt to continue resolution into the next context.
else:
if not self._is_bound(components[0]):
raise NameNotFoundError(components[0])
next_context = self._get_next_context(components[0])
next_context.destroy_subcontext('/'.join(components[1:]))
return
def unbind(self, name):
""" Unbinds a name. """
if len(name) == 0:
raise InvalidNameError('empty name')
# Parse the name.
components = self._parse_name(name)
# If there is exactly one component in the name then the operation
# takes place in this context.
if len(components) == 1:
atom = components[0]
if not self._is_bound(atom):
raise NameNotFoundError(name)
# Lookup the object that we are unbinding to use in the event
# notification.
obj = self._lookup(atom)
# Do the actual unbind.
self._unbind(atom)
# Trait event notification.
self.object_removed = NamingEvent(
old_binding=Binding(name=name, obj=obj, context=self))
# Otherwise, attempt to continue resolution into the next context.
else:
if not self._is_bound(components[0]):
raise NameNotFoundError(components[0])
next_context = self._get_next_context(components[0])
next_context.unbind('/'.join(components[1:]))
return