Re: [Boost-users] [foreach] boost_foreach_is_lightweight_proxy doesn't work

From: Raider (sraider_at_[hidden])
Date: 2007-07-24 07:58:37

> It's not wrong to want that. But it is for important safety reasons that 
> BOOST_FOREACH treats copies of containers as const. In some of the 
> examples you've shown so far, you're trying to proxy a temporary object 
> so you can modify it. That's never going to work. Like this:
> 
>> for (xxx::iterator it(GetVector().begin(), end(GetVector().end());
>>      it != end; ++it) { modify(*it); }
> 
> That's not even valid C++. But even if it were and GetVector() returns a 
> temporary object or a proxy to a temporary object, the vector will be 
> destroyed before you can iterate it. The interface I chose preserves 
> object lifetimes and prevents inadvertent mutation of temporary objects. 
> Weakening its guarantees is a bad idea.

Eric, thanks for detail explanation! The several tradeoffs you met, I 
think you choose the right solution.