From: Ion Gaztañaga (igaztanaga_at_[hidden])
Date: 2007-10-23 11:56:26
Markus Schöpflin escribió:
> Hello,
>
> in the file mem_algo_common.hpp there is a class
> basic_multiallocation_iterator (line 50ff).
>
> This class contains both definitions for operator* and operator->, where
> operator* is implemented as:
>
> value_type operator*() const
> {
> value_type v = (char*)detail::get_pointer(next_alloc_.next_);
> return v;
> }
>
> and operator->() as:
>
> pointer operator->() const
> { return &operator*(); }
>
> The second definition confuses both me and my compiler. Does &operator*()
> actually mean &(*this)? If yes, wouldn't this mean that operator-> returns
> the address of a stack allocated result variable, namely the address of the
> result of operator*? If no, what does this actually mean?
You are right. I'm returning the address of a temporary! I think
conceptually the iterator is wrong. I should return char & for
operator*() instead of char *. char *should be returned by operator->.
However this makes the code uglier:
multiallocation_iterator it = ...
for(...)
//placement new
new(&*it++) T();
instead of
for(...)
//placement new
new(*it++) T();
If I want basic_multiallocation_iterator to be a well-formed iterator I
need to define operator->() so I think I'll need to change the interface
of this class (I doubt anyone is using it). Give me some time to change
it and pass the tests again.
Regards,
Ion