"On Aug 11, 2016, at 9:04 PM, dangerwillrobinsondan...@gmail.com wrote: >> On Aug 12, 2016, at 9:16 AM, Steve Sisak <sgs-li...@codewell.com> wrote: >> >> There’s a standard idiom where immutable classes frequently have mutable >> subclasses (which expose the mutating methods). >> >> In this case, it’s common for the immutable (super)class to adopt NSCopying >> and the mutable subclass to also adopt NSMutableCopying. >> >> This way if you want to add an object to a collection, calling -copy has the >> effect of freezing the current value — the immutable class can optimize this >> by just returning a new reference to the same object, but the caller doesn’t >> have to know whether the object was immutable or a mutable subclass. > > Almost. > > The design pattern for this is the class cluster. > Where the public interfaces may produce private subclasses that handle and > respond appropriately to the messages that make them one or the other.
Actually, to be pedantic, class cluster is an implementation detail — was trying to impedance match to OP’s experience level. Was speaking purely in terms of public interfaces (since he’s a consumer rather than implementor). -Steve _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
