Arkadiy Vertleyb wrote:

"Peter Dimov" <pdimov@mmltd.net> wrote

...

In 1.33, you can't use boost::bind with Lambda's placeholders. Either use Bind's ::_1 placeholder, or use boost::lambda::bind.

In 1.35, the code will work even with Lambda's placeholder.

Is 1.35 correct or did you mean 1.34?

1.35 is correct. 1.34 has been closed for new features for quite a while.

Just an idea -- is it possible to have one universal set of placeholders in boost? Bind, Lambda, MPL, and possibly other libraries could then use some sort of redirection to their specialized placeholders... Might help to avoid some confusion.

This isn't possible in general, but in 1.35 boost::bind implements the TR1 is_placeholder extension mechanism that allows anybody to define their own placeholders. I've already made Lambda's placeholders compatible with boost::bind. Bind's placeholders can't be made compatible with Lambda, since the latter places more requirements on its placeholders; they are fully-featured lambda expressions.

Thanks Peter, But how exactly do I specify _1? I have the same error if I do not specify any name space (as it is shown in the example) boost::_1 is not defined boost::bind::_1 generates "fatal error C1001: INTERNAL COMPILER ERROR" I do not know which error I like the best :) This is the code: #include <vector> #include <algorithm> #include <boost/bind.hpp> int main(int argc, char **argv) { typedef std::vector<std::vector<bool> > T2Dimensional; T2Dimensional vec; std::for_each(vec.begin(),vec.end() ,boost::bind(&std::vector<bool>::resize,_1,10)); return 0; } Thanks. Peter Dimov wrote:

Alexander Shyrokov wrote:

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I want to call a member function with a parameter from within an algorithm.

http://boost.org/libs/bind/bind.html#with_algorithms gives an example:

void animation::advance(int ms); std::vector<animation> anims; std::for_each(anims.begin(), anims.end(), boost::bind(&animation::advance, _1, ms));

I am using boost::lambda:: before _1. I get an error error C2825: 'F::result_type': cannot form a qualified name

I am using MS VC7.1 and boost_1_33_1

Any ideas why this does not work? Thanks.

In 1.33, you can't use boost::bind with Lambda's placeholders. Either use Bind's ::_1 placeholder, or use boost::lambda::bind.

In 1.35, the code will work even with Lambda's placeholder.

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-- Regards, Alexander. http://sjcomp.com

Thanks! That solved the problem. Thanks a lot. Peter Dimov wrote:

...

#include <vector> #include <algorithm> #include <boost/bind.hpp>

int main(int argc, char **argv) { typedef std::vector<std::vector<bool> > T2Dimensional; T2Dimensional vec; std::for_each(vec.begin(),vec.end() ,boost::bind(&std::vector<bool>::resize,_1,10)); return 0; }

Your code is fine, sort of. The problem is that vector<>::resize takes two arguments. The second one has a default, but this information is lost when the pointer to member &std::vector<bool>::resize is taken. So you have to pass a value for it.

std::for_each(vec.begin(),vec.end() ,boost::bind( &std::vector<bool>::resize, _1, 10, false ) ); -- Regards, Alexander. http://sjcomp.com

David Abrahams <dave <at> boost-consulting.com> writes:

And then there's the minor detail that you're not allowed to take the address of standard library (member) functions... to be technically portable and correct, you need to write a wrapper, e.g.

struct resize_vector_bool { template <class V, class N> void operator()(V& v, N n) const { v.resize(n); } };

and then you can go back to using two arguments:

std::for_each( vec.begin(), vec.end() , boost::bind( resize_vector_bool(), _1, 10));

If I do it the correct way I get: boost_1_33_1\boost\bind.hpp(63) : error C2039: 'result_type' : is not a member of 'Geometry::resize_vector_bool' I've tried to convert it into a function, but it did not help. Why does that happen? Thanks.

...

...

struct resize_vector_bool

Should'nt that be

struct resize_vector_bool : public std::binary_function<V,N,void> ?

Thanks Hendrik, it solved the problem though I had to define template parameters. This is the final working version: template <class V, class N> struct resize_vector_bool : public std::binary_function<V,N,void> { void operator()(V& v, N n) const { v.resize(n); } }; std::vector<std::vector<bool> > vec; std::for_each( vec.begin(), vec.end() , boost::bind( resize_vector_bool<std::vector<bool>,int>(), _1, 10)); -- Regards, Alexander. http://sjcomp.com

Peter Dimov wrote: [...]

1. Define result_type:

struct resize_vector_bool { typedef void result_type;

template<class V, class N>

void operator()(V& v, N n) const { v.resize(n); } };

;-)