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

Subject: Re: [Boost-users] [bind] How to dereference _1 in a boost::bind expression
From: Peter Barker (newbarker_at_[hidden])
Date: 2008-10-02 09:36:01

On Thu, Oct 2, 2008 at 11:45 AM, Sven Gaerner <sgaerner_at_[hidden]> wrote:
> On Thu, 2 Oct 2008 11:12:54 +0100
> "Peter Barker" <newbarker_at_[hidden]> wrote:
>
>> Hello,
>>
>> Here's an example of my problem:
>>
>> #include <algorithm>
>> #include <vector>
>>
>> #include <boost/bind.hpp>
>>
>> class TheClass
>> {
>> };
>>
>> void accept(TheClass& tc)
>> {
>> }
>>
>> int main()
>> {
>>       std::vector<TheClass*> 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_at_[hidden]
>> 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