Re: [boost] Re: Any Interest In a Raw Memory Buffer

From: Brian Gray (briangray_at_[hidden])
Date: 2003-03-04 21:39:06

On Tuesday, March 4, 2003, at 05:36 PM, Andrei Alexandrescu wrote:
> "Brian Gray" <briangray_at_[hidden]> wrote in message
> news:134BA7DC-4E86-11D7-81C4-00039375675E_at_mac.com...
>> I can see how vector<Derived*> might benefit from conversion to
>> vector<Base*>, but we're talking about contiguous memory here.  Very
>> subject to raw object size, so there's no way to cast between the two
>> and preserve object hierarchies if they're not pointers.
>
> The conversion vector<Derived*> to vector<Base*> is unsound. What, are 
> we
> going the way of Java containers? :o)

Heh, maybe I could have phrased it a bit better.  Yes, a vector of 
Deriveds IS_NOT_A vector of Bases.  But I can see how a developer might 
wish to make the conversion, however ill-advised.  An int IS_NOT_A 
float, but people often want to convert between them.  What the OP was 
suggesting is a whole other ball of wax.  It would be like having a 
struct, and casting it to another arbitrary struct, mapping the memory 
to whatever members happened to sit there.  Or bitwise replication of a 
float's representation into an int variable.  Quite a mess.

  -- Brian