Re: [Boost-users] [lambda] logical operators related errors

From: Dizzy (dizzy_at_[hidden])
Date: 2007-03-29 11:05:12

Hello

On Thursday 29 March 2007 17:42, Nat Goodspeed wrote:
> -----Original Message-----
> From: boost-users-bounces_at_[hidden]
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Dizzy
> Sent: Thursday, March 29, 2007 5:05 AM
> To: boost-users_at_[hidden]
> Subject: [Boost-users] [lambda] logical operators related errors
>
> #include <boost/lambda/lambda.hpp>
> #include <boost/bind.hpp>
> #include <boost/mem_fn.hpp>
>
> int main()
> {
> 	using boost::bind;
> 	using boost::mem_fn;
>
> 	A a1("str1", "str2", "str3");
> 	A a2("str2", "str1", "str3");
>
> 	eval(((bind(&A::s1, _1) < bind(&A::s1, _2)) && (bind(&A::s2, _1)
> <
> bind(&A::s2, _2)))(a1, a2));
> }
>
> This errors compiling about operator&& no match found.
>
> [Nat] I think the problem may be that you're mixing boost::bind with
> plain operators. Try using boost::lambda::bind instead and see if you
> get farther.

Ok, using lambda::bind and lambda::_1, lambda::_2 it seems to work. However, I 
thought that boost::bind since 1.33 version returns a functor that can be 
used for lambda composition and it's overloaded operators (please excuse me 
if I just said something stupid, I'm a beginner with all this lambda/bind 
terms), hence would have explained to me why operator< did work with 
boost::bind without requiring boost::lambda::bind such as operator&& seems to 
require.

Any idea why operator< works with the boost::bind functors and operator&& 
doesn't ? Or something else that I'm missing (such as there have been made 
special overloads for operator< to work with boost::bind functors).

Thanks!

-- 
Mihai RUSU					Email: dizzy_at_[hidden]
GPG : http://dizzy.roedu.net/dizzy-gpg.txt	WWW: http://dizzy.roedu.net
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