Re: [Boost-users] boost::bind to member variables

From: Nico Galoppo (nico_at_[hidden])
Date: 2006-03-30 08:42:09

Hi Stuart,

thanks for the solution. It seems like what I am looking for, I'll try it out 
asap. However, I am confused by the typedef below.

typedef int A::*Setter;

Could you explain what is going on here?

--nico

Stuart Dootson wrote:
> On 3/30/06, Nico Galoppo <nico_at_[hidden]> wrote:
> <snip>
> 
>>Well, I probably over-simplified the problem. What I would really like to do is
>>manipulate data members of all instances in a container, where the data member
>>is given as an input parameter.
>>
>>struct A {
>>  int value;
>>  int othervalue;
>>}
>>
>>container<A> array;
>>
>>void f(container<A> & array, membervarref)
>>{
>>   BOOST_FOREACH(container<A>::value_type& element, array)
>>         bind(membervarref, element) = 3;
>>}
>>
>>f(array, &A::value);
>>f(array, &A::othervalue);
>>
>>--nico
>>
> 
> 
> Well, how about this (using you definition of A):
> 
> typedef std::vector<A> As;
> typedef int A::*Setter;
> 
> void Set(As& as, Setter setter, int value)
> {
>    using namespace boost::lambda;
>    std::for_each(as.begin(), as.end(), bind(setter, _1) = value);
> }
> 
> void func()
> {
>    As as;
> 
>    Set(as, &A::a, 3);
>    Set(as, &A::b, 5);
> }
> 
> If you want to decouple from A a bit more, you could change the
> definition of Setter like below
> 
> typedef boost::function<int&(A&)> Setter;
> 
> and it'll compile and run OK (tested with VC7.1).
> 
> Stuart Dootson
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
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