Re: [boost] [shared_array] Why not in C++11 ?

Subject: Re: [boost] [shared_array] Why not in C++11 ?
From: Peter Dimov (lists_at_[hidden])
Date: 2013-07-08 11:54:03

Rob Stewart wrote:
...

> That's error-prone. Why not provide (non-zero) capacity when using 
> make_shared(), and leave the non-make_shared() usage with a zero capacity?

That's not very convenient. Suppose you get a T* from some place and need to 
pass shared_ptr<T[]> to another that requires a known size. You know the 
size, but you won't be able to pass it.

It's also error prone. If you have an interface that takes shared_ptr<T[]> 
and size_t, you can tell that the code is passing a size by mere visual 
inspection. But if the function only takes a shared_ptr<T[]>, and if 
shared_ptr<T[]> might or might not have a size, it's not immediately obvious 
whether you are passing a size or not. Maybe you are, maybe you aren't; 
we'll have to wait until runtime and see.

Finally, zero is technically a legitimate value for the size, signifying an 
empty array, so overloading it to denote "unknown" may not be the best 
option.