Re: [Boost-users] multi_array, resize and default constructable

From: gast128 (gast128_at_[hidden])
Date: 2008-08-21 04:55:28

Dr Johann A. Briffa <j.briffa <at> ieee.org> writes:

> > ...Any new elements in the array are default constructed..."
> >
> > It is thus not possible providing a default fill element?
> >   
> The default fill element is the default value of the type. For example, 
> if you have a multi_array of doubles, on array construction (or resize) 
> all new elements will be 0.0. You cannot change this value without 
> changing the default value of the underlying type.
> Johann

I understand that, built in types are also defined for default construction.

However I had a need here to override that default. Looking at the 
vector::resize(), it offers an overload function for specifying the fill 
element.

The case I needed was soemthing likea std::pair<HANDLE, nstring>, where the 
the default handle is -1 (i.e. std::pair<HANDLE, nstring> default(-1, ""));. 
Of course this can be solved by promoting this to a full blown struct with 
default ctor, but I donot like to introduce extra structures for just bundling 
data.