Re: [boost] Graph library concept check problem

From: David Abrahams (dave_at_[hidden])
Date: 2006-05-02 08:21:20

Matthias Troyer <troyer_at_[hidden]> writes:

> On Apr 28, 2006, at 4:54 PM, Daniel Walker wrote:
>
>> On 4/28/06, Matthias Troyer <troyer_at_[hidden]> wrote:
>>> Hi,
>>>
>>> Trying to compile our ALPS project sources (http://alps.comp-
>>> phys.org) with the CVS HEAD I encountered a number of problems with
>>> the BGL concept checking. In particular on MacOS X, using the  
>>> Apple g+
>>> + 4.0.1, I encounter problems in depth_first_search.hpp with:
>>>
>>> Matthias
>>
>> I don't believe models of the Graph or DFSVisitor concepts are
>> required to be default constructable.
>>
>> I tried to take a look at this compiling ALPS-1.3a1, but couldn't
>> reproduce the error with g++ 4.0.3 on Linux. As far as I can tell
>> neither DFSVisitorConcept nor CopyConstructibleConcept use a default
>> constructor. However, if for some reason your (custom) visitor class
>> tries to default construct a graph in a member function
>> (initialize_vertex(), start_vertex(), etc.) this could cause the
>> error. Could you give a specific example of code that causes the
>> error?
>
> I saw the same problem also in other libraries now and it seems to be  
> an issue with concept checking in general on my machine. The default  
> constructors of all data members of the concept checking classes seem  
> to get instantiated somehow. I'll try to track this down.

I've been working on the concept checking library and may have caused
some churn on the CVS head.  Sorry about that.

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