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Re: Exception support (was: Feeding NSUnarchiver bad data can cause crash)

On Jun 3, 2004, at 9:46 AM, Ondra Cada wrote:

do you understand the new directives? Namely, do you happen to know

- how (in)compatible they happen to be with the NS_... macros?

Don't know exactly. I believe that they are compatible however not likely sensibly intermixed in the same code block, in a given block use one or the other.

- are they less or more efficient?

Well in theory @try will be more efficient in the long run because of how it is supported. It is supported at the compiler level so things are directly injected as needed, they are not macro based. Apple is panning to advance them as things they leverage get rework and improved. Again I really haven't dug deep into it to see the difference in the resulting code (given backward compatibility currently with NS_DURING... it may not be much different).

- what caveats there are mixin' them with NS_... macros? (seems with @throw you can raise anything, but NS_HANDLER would suppose there's an NSException subclass in localException, would it not?)

Don't know.

- which way is better for which situations?

I would say that @try/@catch/@finally/@synchronize is always better IMHO. They are cleaner/clearer in meaning/reading and they work with each other well and things like returns, breaks, etc. in a code block. Also it is nice to have the recursive mutex released for you automatically on exiting a synchronize block even in the case of an exception.

Perhaps I've overlooked something, but save for a short info along lines of "are backward compatible with NS... macros, incompatible with C++ exceptions" in the release notes I've found nothing on this subject yet...

I do know that Apple folks would love to make the @try... stuff support C++ exceptions directly without any extra work on our part. I cannot find the email that stated this now but I believe it was on the objective-c list a while back.

-Shawn
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References: 
 >Re: Feeding NSUnarchiver bad data can cause crash (From: "Douglas A. Welton" <email@hidden>)
 >Re: Feeding NSUnarchiver bad data can cause crash (From: Shawn Erickson <email@hidden>)
 >Exception support (was: Feeding NSUnarchiver bad data can cause crash) (From: Ondra Cada <email@hidden>)



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