Technically, this is actually a fairly deep copy. All of the object
structure should be replicated, but the actual dictionary storage will
be shallowly copied::
copy = context.shallow_copy()
copy[key] is context[key] for key in context.keys()
These semantics are useful for saving out checkpointed versions of the
context for implementing an undo/redo stack. They may not be useful for
other purposes.
Returns
-------
copy : IContext
"""
copy = self.clone_traits()
checkpointable_subcontext = adapt(self.subcontext, ICheckpointable)
copy.subcontext = checkpointable_subcontext.checkpoint()
return copy
declareAdapter(
lambda x: DataContext(subcontext=x),
[ICheckpointable, IListenableContext, IPersistableContext,
IRestrictedContext],
forProtocols=[IContext],
)
# HasTraits.clone() semantics force a shallow copy of these traits. If
# you store mutable objects like lists and dicts using Any traits, then
# HasTraits.clone() will pass along the reference instead of making
# a shallow copy. Modifications to that trait in the original will
# propagate to the copy. This is not desirable.
#
# However, if the trait is declared with copy='shallow' metadata, then
# HasTraits.clone_traits() will do the right thing. This is preferred.
#
# Subcontexts of either DataContext or MultiContext should be adaptable
# to the ICheckpointable interface. An adapter for dicts is provided
# here.
class CheckPointableDictAdapter(object):
""" Adapt a dictionary to the ICheckpointable interface.
"""
def __init__(self, dict):
self.dict = dict
def checkpoint(self):
return self.dict.copy()
declareAdapter(
CheckPointableDictAdapter,
[ICheckpointable],
forTypes=[dict],
)