Terry Reedy wrote:
I guess so, yes. My method would be something like what Jacob said, abusing the memo dict to pass the copying mode. But I thought perhaps we can set a standard way for specifying different copy modes, because otherwise I'll do my memo hack and someone else will do his different memo hack and it won't be compatible.
Perhaps you can post a recipe at the Python Cookbook. People who care about compatibility can follow the same recipe.
Alternatively, this use case strikes me as being rather similar to the various flatten() recipes out there that accept a list of "atomic" types to avoid flattening iterable-but-not-really-a-container types such as strings. The analogy currently breaks due to copy.deepcopy() being set up with each __deepcopy__ method doing its own recursion rather than constructing a graph of mutable (to be copied) and immutable members (to be referenced) down the chain of the object graph. More flexible (but significantly harder) than adding a copy mode would be defining a protocol for exposing the object graph in a standardised fashion. __iter__ in conjunction with __dict__ would get you a fair way, but there would be a lot of complications. Cheers, Nick. -- Nick Coghlan | ncoghlan@gmail.com | Brisbane, Australia ---------------------------------------------------------------