Boost.Lambda - Invoking functors stored in a vector

From: Thomas Wenisch (twenisch_at_[hidden])
Date: 2002-07-29 16:47:47

Hi all,

I am storing a set of functors to be invoked in a vector, like this:

std::vector< boost::function<void> > functors;

At a later time, I would like to invoke each of the functors in the
vector.  I am trying to do this using Boost.Lambda, to start learning
about the Lambda library, but I can't figure out what to write.

if I write:

std::for_each(functors.begin(), functors.end(), _1);

None of the functions are invoked.

if I try:

for_each(funtors.begin(), functors.end(), _1());

I get compile errors.  I suspect this is because the lamda expression is
being executed immediately instead of getting passed in to for_each.

Everything works fine when I use a separate Invoker function in the
usual fashion, like this:

void Invoker( boost::function<void> functor) {
   functor();
}

std::for_each(funtors.begin(), functors.end(), Invoker);

How can I get the lambda library to invoke each function in the
vector?  More generally, if the functions were function<void, T>, how
could I bind the T parameter in the lambda expression?

Thanks for any help,
Tom Wenisch
Computer Architecture Lab
Carnegie Mellon University