Re: [Boost-users] trying to build custom property_map

Subject: Re: [Boost-users] trying to build custom property_map
From: Sandeep Gupta (gupta.sandeep_at_[hidden])
Date: 2010-04-01 16:22:31

On Thu, Apr 1, 2010 at 12:41 PM, Jeremiah Willcock <jewillco_at_[hidden]>wrote:

> On Thu, 1 Apr 2010, Sandeep Gupta wrote:
>
>  It seems that the error occurs when I don't define   "typedef int&
>> reference" for the property map
>> class.  The confusing part is that when I compile with boost_1_42 I get
>> the error
>>
>> boost_1_42_0/boost/property_map/property_map.hpp:33: error: no type named
>> 'reference' in 'struct
>> VecMap'
>>
>> Which is expected. However, If I compile against the trunk I get undefined
>> value_type error instead of
>> undefined reference error.
>>
>> boost-trunk/boost/pending/disjoint_sets.hpp:65: error: no type named
>> 'value_type' in 'struct
>> boost::property_traits<VecMap>'
>>
>> Something surely is amiss here. Most likely in the disjoint_sets.hpp, I
>> believe.
>>
>> Thanks
>> -Sandeep
>>
>
> The behavior of property_traits changed in newer versions of Boost.  Now,
> nothing in property_traits is defined for a property map unless it has all
> four required members (key_type, value_type, category, and reference).
> Previously you would only get an error for those that were missing. This
> change was necessary so including Boost.Graph and Boost.Variant in the same
> program would work.
>
>
I see. Although I would say this change introduces a non-friendly error
message. It threw me out-of-the-loop to see the compiler complain about
value_type when it was already defined. Would it be possible to emit error
at the property_map level itself.

For now I am good. Thanks so much for looking.

-Sandeep