Hello,
I have a question about Cocoa API design. I think I can give a concrete example
to best explain what the goal is. Assume I have an Inventory service and I need
to write a client API that deals with it. Goals:
- The API should allow me to add, update, delete and search items
- These operations should be asynchronous
Path #1:
Public method: - (void)addInventoryItem:(MyInventoryItem *)inventoryItem;
Implement a protocol for each of the actions (i.e. add, update, delete and
search. See URLConnection, "Connection Completion" section) Example:
- Delegate method if successful: -
(void)itemAdditionDidSucceed:(MyInventoryItem *)accountInfo;
- Delegate method if failure: - (void)itemAddition:(MyInventoryItem
*)accountInfo didFailWithError:(NSError *)error;
Pros: the delegate method can receive specific data objects specific to the
operation (i.e. MyInventoryItem for addInventoryItem vs NSArray for
searchInventory)
Cons: the protocol could end up being verbose, with many delegates to be
implemented (i.e. success/failure for add, update, delete and search... 8
methods in total)
Path #2:
Implement a protocol with two methods: success and failure (see URLConnection,
"Connection Completion" section)
Implement an action class that encapsulates the action (i.e. add, update,
delete and search) and the actual data needed for the operation
Public method: - (void)addInventoryItem:(MyInventoryAction *)inventoryAction;
Delegate method if successful: - (void)actionDidSucceed:(MyInventoryAction
*) inventoryAction;
Delegate method if failure: - (void)action:(MyInventoryAction *)
inventoryAction didFailWithError:(NSError *)error;
Pros: simplifies the number of delegate methods
Cons: when the delegate method gets called, we have to introspect to obtain the
action and associated data. Also, the data could be a single inventory item
(i.e. add, update, delete) or an array of them (i.e. search), so we would have
to cast the return type (id since it's generic) to its proper class based on
the type of action.
Which option do you feel is better? Would you consider a different solution? I
really don't mind if the implementation is more complex if that makes the life
of the developer easier. Perhaps Path #2 is better because it would simplify
the Client code, but I would like to hear what other developers think.
Thanks in advance,
-- Tito
_______________________________________________
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:
http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
