Re: [Boost-users] Using lambda for sort

Olaf van der Spek wrote:

On 8/9/07, Peter Dimov wrote:

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Olaf van der Spek wrote:

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sort(countries1.begin(), countries1.end(), _1->second > _2->second);

sort( countries1.begin(), countries1.end(),

bind( &countries_t::value_type::second, *_1 ) > bind( &countries_t::value_type::second, *_2 )

Thanks, that did the trick. I didn't know you could use bind like this too. But why does the simpler syntax not work?

Due to the way operator-> overloading works, it's hard to make _1->second do what you want (and impossible for arbitrary identifiers and not just 'second'.) The closest you can get with Lambda is _1 ->* &countries_t::value_type::second.