Re: [Boost-users] conflicting intmax_t definitions - Boost 1.53 and gcc 4.8 incompatibility?

Subject: Re: [Boost-users] conflicting intmax_t definitions - Boost 1.53 and gcc 4.8 incompatibility?
From: John M. Dlugosz (ngnr63q02_at_[hidden])
Date: 2014-01-26 20:51:21

On 1/21/2014 9:27 AM, Leon Mlakar wrote:
> On 21/01/14 16:20, John M. Dlugosz wrote:
>> On 1/20/2014 6:32 AM, Nate Finch wrote:
> Or alternatively avoid using "using" and use fully qualified names (e.g. boost::intmax_t)
> - there's nothing wrong with this, either.
>

Actually, there are cases where that's not right, when writing templates.  In particular, 
swap(x,y) where x and y are of type T.  You need to write it unqualified to have it find 
swap via argument-dependent lookup, but when T is int it needs to find std::swap.  The 
idiom (as far as I know) is to declare `using std::swap;` in the function body.

FWIW, I often like having common things ready for unqualified use in my CPP files, such as 
`string` and `make_shared`.  I find it easier to read, and it keeps the lines shorter so 
the real expression fits in one single-gaze clump of reading text.

For something like boost::intmax_t where the code wants to emphasize which one is being 
called, qualifying helps with future maintenance.  Like most classes use std::shared_ptr 
but others (e.g. asio) use boost::shared_ptr, so it's awkward when writing the functions 
that use both of them.

In headers, scope-pollution is prohibited (I mean by policy, not by the language).  For 
most coders that means the rule is equivalent to "don't use `using` in headers".