Re: [Boost-users] Library Interface Design

From: Matthias Hofmann (hofmann_at_[hidden])
Date: 2006-09-18 08:39:58

"David Abrahams" <dave_at_[hidden]> schrieb im Newsbeitrag 
news:87bqphhxjl.fsf_at_pereiro.luannocracy.com...
> David Walthall <walthall_at_[hidden]> writes:
>
>> The only time I have found it useful to have default-constructed objects
>> that are otherwise unusable is when I need to store them in a map or
>> other container that requires a default constructible object.
>
> No standard containers have that requirement, though.

This seems to be another defect, as the standard also defines the following 
constructor:

explicit vector(size_type n, const T& value = T(),
const Allocator& = Allocator());

Now how is the following code supposed to compile:

#include <vector>

struct X
{
    X( int ) {}
};

void f()
{
    // Error: No default constructor for X.
    std::vector<X> v( 5 );
}

-- 
Matthias Hofmann
Anvil-Soft, CEO
http://www.anvil-soft.com - The Creators of Toilet Tycoon
http://www.anvil-soft.de - Die Macher des Klomanagers