Mac Apps That Use Garbage Collection Must Move to ARC

[Walter Bright via Digitalmars-d]

On 2/23/2015 1:50 AM, Manu via Digitalmars-d wrote:
>> 1. Increment and decrement, ESPECIALLY DECREMENT, is EXPENSIVE in time and
>> bloat because of exceptions. Swift does it by NOT HAVING EXCEPTIONS. This is
>> not an option for D.
>
> This is going to sound really stupid... but do people actually use
> exceptions regularly?

It doesn't matter if they do or not. It's a feature of D, and has to be 
supported. The only time it won't matter is if the intervening code is all 
'nothrow'.


> You say that's a terminal case? Generating code to properly implement
> a decrement chain during unwind impacts on the non-exceptional code
> path?

Since you don't believe me :-), write some shared_ptr code in C++ using your 
favorite compiler, compile it, and take a look at the generated assembler. I've 
asked you to do this before.

It's necessary to understand how exception unwinding works in order to 
pontificate about ARC.


>> 3. Memory safety is a requirement for any ARC proposal for D. Swift ignores
>> memory safety concerns.
> What makes RC implicitly unsafe?

You already know the answer - saving pointers to the RC object's payload that 
then outlive the RC'd object.