Re: [Boost-users] [Lambda] Getting the bind incantation correct.

On Mon, May 23, 2011 at 11:42 AM, 肖锋 wrote:

On Mon, May 23, 2011 at 6:25 PM, Robert Jones wrote:

...

Hi All

I'm trying to use std::vector::push_back() within a Boost.Lambda expression, but am finding it impossible to bind correctly. Can anyone tell me what I'm doing wrong in this code?

Thanks in advance,

- Rob.

#include <vector> #include #include

void f( ) { namespace ll = boost::lambda; using boost::function;

typedef unsigned char Id; typedef std::vector<Id> Ids;

ll::placeholder1_type x;

Ids ids; void ( Ids::* push_back )( const Ids::value_type & ) = & Ids::push_back;

function my_push = ll::bind( push_back, ids, x ); // Line 18

Change ids to ll:var(ids) because the operation 'push_back' needs a mutable object.

...

(void)my_push; }

...

g++ ignore.cpp

[...lots of template instantiation errors, then...]

ignore.cpp:18: instantiated from here /usr/include/boost/lambda/detail/actions.hpp:96: error: no matching function for call to ‘boost::lambda::function_adaptor::*)(const unsigned char&)>::apply(void (std::vector::* const&)(const unsigned char&), const std::vector&, unsigned char&)’ /usr/include/boost/lambda/detail/actions.hpp:96: error: return-statement with a value, in function returning 'void'

Ok, many thanks, that worked. But why isn't "ids" mutable on its own? - Rob.