On 07/13/2010 04:15 PM, Vladimir Panteleev wrote:
On Tue, 13 Jul 2010 23:16:30 +0300, Andrei Alexandrescu
<[email protected]> wrote:
Not quite. New is different because it is a primitive - it can't be
implemented as a function (well it could if it user placement new, but
we're back to square one). In contrast, delete already knows the type
of the object it's destroying and can call the destructor manually so
it is easy to implement as a regular function.
Sorry, not following you here. Why can't new be implemented as a
templated function which takes the type of the object to create as a
template parameter? Isn't it just allocation, copying over T.init, then
calling the constructor with whatever arguments the user passed?
In D it's possible to call the constructor by issuing __ctor(). In C++
there is no way, hence the presence of a language primitive.
Doesn't that only support my argument that new *can* be implemented as a
function?
It does. I was explaining how come new was a keyword in C++ followed
then by imitation by Java (where it's completely unneeded) and D.
You should use malloc() and free() for manual memory management and
the GC for automatic memory management. Each of these two is
ill-suited for carrying the other's job.
Thanks, that was really what I was missing from the picture.
However, D allows overloading new/delete for custom allocators[1] - this
can be used for a cleaner way to allocate objects in unmanaged memory. I
don't see why this use of the delete keyword should be deprecated.
[1]: http://digitalmars.com/d/2.0/memory.html#newdelete
That's gone too. It was a thoroughly mistaken feature, and it's an
accident that it still compiles and runs.
We need to plug all the holes in the dam(n).
Andrei
