On Tue, Nov 30, 2010 at 3:20 PM, Steven Watanabe <watanabesj@gmail.com> wrote:
AMDG


On 11/30/2010 7:06 AM, Robert Jones wrote:
I'm not sure if this is a stupid question, but is there a runtime equivalent
of boost.mpl's identity
metafunction?

Something that just returns it's single argument, eg.,

template<typename T>  T identity( T t ) { return t; }

I think it's trivially simple to write, but I wonder if it already exists in
Boost or
indeed the STL?

(I need this because I need to pass a function object which simply returns
an
object I already have - maybe I've missed a more obvious method?)


boost::lambda::_1?


Thx Steven - as usual exactly the right answer to the question.

I however have realised I'm asking completely the wrong question. What I in fact
want to do is to create on the fly a nullary function object which returns a constant
value.

Possibly this is what lambda::constant does?

Thx, Rob.