compose.hpp / additional functions?

From: Daniel Frey (daniel.frey_at_[hidden])
Date: 2001-05-15 03:28:24

Hi,

while using function objects more and more, it seems to me that either
I'm missing something or the STL and/or boost's compose.hpp is missing
something :)

If a have a common template class working with a binary function f(a,b),
I instantiate it to perform operations like a/b, a-b, (a-1)*b which is
easy. But sometimes, I need to return just 'b', I mean f(a,b)=b. I could
define it as f(a,b)=0*a+b, but that is IMHO bad.

I haven't seen any function in the STL or in boost's compose.hpp to
select just the first or second parameter. If they exists and I missed
them, please point me to the right header. If they don't exist: Should
we add 'select1st' and 'select2nd' to compose.hpp? Or are there better
names?

Regards, Daniel

--
Daniel Frey
aixigo AG - financial training, research and technology
Schloß-Rahe-Straße 15, 52072 Aachen, Germany
fon: [phone], fax: [phone]
eMail: daniel.frey_at_[hidden], web: http://www.aixigo.de