Re: [boost] [parameter] Boost.Graph program not responding at run-time

Subject: Re: [boost] [parameter] Boost.Graph program not responding at run-time
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2011-12-03 15:16:22

On Sat, 3 Dec 2011, Lorenzo Caminiti wrote:

> On Sat, Dec 3, 2011 at 2:28 PM, Jeremiah Willcock <jewillco_at_[hidden]> wrote:
>> On Sat, 3 Dec 2011, Lorenzo Caminiti wrote:
>>> If I move the call to boost::depth_first_search into a template
>>> depth_first_search_impl and out of the Boost.Parameter function body,
>>> the code compiles (both MSVC and GCC with latest Boost from trunk) but
>>> the executable runs forever and prints nothing to cout... What am I
>>> doing wrong?
>>
>> I tried your code with GCC 4.6.0 and it worked just fine as you pasted it
>> below.  I get:
>>
>> order of discovery: u v y x w z
>> order of finish: x y v u z w
>>
>> as the result.  You are returning an invalid pointer from
>> default_color_map(), though; &colors[0] becomes invalid when colors is
>> destroyed at the end of the function.
>
> Oops... thanks, that was actually the issue, after I fixed the invalid
> pointer the code runs fine.
>
> BTW, what's the best way to generate a default_color_map for
> Boost.Graph like the one below?

Probably the simplest is to use shared_array_property_map; you can return 
those from functions as shallow copies.  If you write the default code in 
your DFS function itself, you can create the vector there and pass an 
iterator_property_map to the underlying DFS code (that is what the current 
parameter defaulting code does).

-- Jeremiah Willcock