Re: [Boost-users] How to figure out if a boost class does lazy copy or not?

Subject: Re: [Boost-users] How to figure out if a boost class does lazy copy or not?
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2010-06-12 19:43:38

AMDG

Peng Yu wrote:
> I need to construct some container in a function and return it. I
> think that some container in boost follow lazy copy sematics but some
> don't.
>   

Meaning copy on write?  I don't think that any containers in
Boost use copy on write.

> For example, if tr1::unordered_map uses lazy copy, then I can return
> an object of tr1::unordered_map. Otherwise, I should return
> boost::shared_ptr<tr1::unordered_map>.
>   

Are you sure that RVO isn't enough?

> Although this information may be documented for any container that I
> will use, I still think that it is still worthwhile to having my own
> test case to figure it out, because it may not easy to find such
> information in the document. I'm wondering if there is a generic way
> to test if a container use lazy copy or not without reading the actual
> implementation of the class?
>   

In Christ,
Steven Watanabe