Re: [boost] [ptr_container]boost::ptr_map

From: David Abrahams (dave_at_[hidden])
Date: 2005-10-09 19:32:03

Thorsten Ottosen <nesotto_at_[hidden]> writes:

>> ptr_map<>::insert(key, value) function is taking first argument by non-const 
>> reference. Is it missing 'const' there? 
>
> No, its an exception-safety issue. if evaluating the first expression could 
> throw, we could leak.

Could you please explain what you're saying?  On the surface, that
sounds like a flawed rationale on many levels.  The arguments to a
function can be evaluated in any order -- they can even be
interleaved.  Taking a parameter by non-const reference does nothing
to prevent the corresponding expression from throwing.  Is this
another example of false user protection?

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com