Re: [boost] Re: How to cast type with vector

From: Jason Earl (Jason_at_[hidden])
Date: 2005-04-26 13:38:16

On 26 Ebr 2005, at 19:23, Caleb Epstein wrote:

> On 4/26/05, Philippe Mori <philippe_mori_at_[hidden]> wrote:
>
>> Since a Limousine is a Car, you should able to do
>>
>>     Cars.insert(Cars.end(), Limousines.begin(), Limousines.end());
>>
>> at least if you have a recent compiler.
>
> And if you don't mind slicing your objects.  You can't store
> polymorphic types directly in std containers.
>
> -- 
> Caleb Epstein
> caleb dot epstein at gmail dot com
>
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Well that's easy enough to get round, use pointers. if you are storing 
objects in containers, it normally is good practice to use pointers 
anyway because the STL passes data round by value, and not my reference 
/ pointer, and therefore unless your objects are very lightweight 
and/or have copy constructors, then storing objects by value is 
normally a big no-no in most cases.

... One good exception to the rule here would be if you had smart 
pointers, obviously these objects are copied into the container, and 
these are lightweight and implement copy constructors / assignment 
operators. Generally, if you are going to use pointers, depending on 
the complexity of the object life-cycle, it is often wise to use 
something like boost::shared_ptr , as it will reduce the the risks of 
things like dangling pointers etc etc.

Jason