Re: [boost] [range] treating N-ary function with N-1 default args as unary

Subject: Re: [boost] [range] treating N-ary function with N-1 default args as unary
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2012-06-30 12:24:24

Le 30/06/12 06:07, Nathan Ridge a écrit :
> Hi,
>
> Some Boost.Range adaptors, such as 'transformed' or 'filtered', require
> a unary function. The documentation does not formally define "unary
> function", but it's pretty clear what it ought to be: a function (object)
> that's callable with one argument.
>
> Thus, to me, the following is a perfectly valid unary function:
>
> int foo(int a, int b = 0);
>
> as it is callable with one argument.
>
> However, Boost.Range does not accept such a function as an argument to
> 'transformed' or 'filtered'. For example, the following code:
>
> #include<boost/range/adaptor/transformed.hpp>
>
> int foo(int a, int b = 0);
>
> int main()
> {
>      int A[5];
>      A | boost::adaptors::transformed(foo);
> }
>
The following should work

int unary(int a) {return foo(a)};

int main()
{
     int A[5];
     A | boost::adaptors::transformed(unary);
}

I agree that it will be interesting to have a way to make this bar 
transformation using a class template unary

int main()
{
     int A[5];
     A | boost::adaptors::transformed(unary<foo>());
}

Best,
Vicente