Re: [Boost-users] BGL: std::map<Edge, int> needs the < operator

From: Irek Szczesniak (ijs_at_[hidden])
Date: 2006-04-21 16:39:52

Hi,

Thank you all for responding to my post.  Now I have my own operator 
function object for the comparison as you advised:

struct cmp_edge :
   public std::binary_function<Edge, Edge, bool>
{
   bool operator()(const Edge &e1, const Edge &e2) const
   {
     return e1.get_property() < e2.get_property();
   }
};

Now I can use std::map<Edge, double, cmp_edge>.

Thanks & best,
Irek

Jeremy Siek wrote:

> Yes, I also recommend the function object approach. You won't
> have to worry about which namespace the function object
> is in... this avoids the argument dependent lookup issues
> that caused problems for the global operator<.
> 
> Cheers,
> Jeremy
> 
> 
> On Apr 20, 2006, at 10:26 PM, Thomas Costa wrote:
> 
> 
>>write your own total ordering/comparison function object for Edge
>>objects and declare the map type using this function.
> 
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