Re: [Boost-users] [bind] How to dereference _1 in a boost::bind expression

On Thu, 2 Oct 2008 14:36:01 +0100 "Peter Barker" wrote:

On Thu, Oct 2, 2008 at 11:45 AM, Sven Gaerner wrote:

...

On Thu, 2 Oct 2008 11:12:54 +0100 "Peter Barker" wrote:

...

Hello,

Here's an example of my problem:

#include <algorithm> #include <vector>

#include

class TheClass { };

void accept(TheClass& tc) { }

int main() { std::vector cont;

// Compile error - how to dereference _1 ??? std::for_each(cont.begin(),cont.end(),boost::bind(&accept,_1)); }

How can I dereference _1 so I can use the accept function?

Regards,

Pete _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

You don't have to dereference _1. Your accept function must look like this: void accept(TheClass *arg) { } Your std::vector contains pointers to TheClass so std::for_each() passes objects of that type to your functor, in this case a pointer to types of TheClass.

Sven,

I was trying to avoid changing the signature of accept as it has other call sites and I would need to update them. It's what I did in the end though. Thanks,

Pete _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Peter, I didn't think about avoiding to change the signature. Sorry for that. What about using a specific delegate functor? Somethink like that: struct Delegate { void operator()(TheClass *arg) { accept(*arg); } }; And then pass this functor to std::for_each(); std::for_each(cont.begin(),cont.end(), Delegate()); That wouldn't break the signature of the accept function, but it depends on that particular implementation. Sven