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std::allocate_shared takes an allocator to allocate the memory for the
shared_ptr. But a standard library allocator can do more than allocate
memory; it can also construct the object using
std::allocator_traits<A>::construct.

Except that it doesn't. It's specifically said to use placement new.

Shouldn't this be changed to use the traits, so that a user can define
their own traits class and potentially use constructors that are not
publicly accessible without making it easy for the rest of the world to
access them?

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std::allocate_shared takes an allocator to allocate the memory for the shar=
ed_ptr. But a standard library allocator can do more than allocate memory; =
it can also construct the object using std::allocator_traits&lt;A&gt;::cons=
truct.<br><br>Except that it doesn't. It's specifically said to use placeme=
nt new.<br><br>Shouldn't this be changed to use the traits, so that a user =
can define their own traits class and potentially use constructors that are=
 not publicly accessible without making it easy for the rest of the world t=
o access them?<br>

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2013/1/17 Nicol Bolas <jmckesson@gmail.com>:
> std::allocate_shared takes an allocator to allocate the memory for the
> shared_ptr. But a standard library allocator can do more than allocate
> memory; it can also construct the object using
> std::allocator_traits<A>::construct.
>
> Except that it doesn't. It's specifically said to use placement new.
>
> Shouldn't this be changed to use the traits, so that a user can define their
> own traits class and potentially use constructors that are not publicly
> accessible without making it easy for the rest of the world to access them?

This looks like

http://cplusplus.github.com/LWG/lwg-active.html#2070

to me.

- Daniel

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