return type of boost::bind
I wish to store the return value of boost::bind in an intermediate object
to invoke it at a later time. I only ever see examples which combine
the call to boost:bind with the immediate invocation on the returned
object such as:
#include
The return type of boost::bind is fairly indeterminate. In order to call a bound function at a later time, look at boost::function. It does a nice job of holding on to a function that uses boost::bind. --- At Sun, 1 Feb 2004 08:45:43 -0500, Cheenu Srinivasan wrote:
I wish to store the return value of boost::bind in an intermediate object to invoke it at a later time. I only ever see examples which combine the call to boost:bind with the immediate invocation on the returned object such as:
#include
using namespace boost; #include <iostream> using namespace std; double f(int i, double d) { cout << "int = " << i << endl; return d; }
main() { int i = 99; cout << bind(f, _1, 1.234)(i) << endl; }
Instead I'd like to postpone the call to the returned object. What's the type of obj?
main() { int i = 99; WHAT_IS_MY_TYPE obj = bind(f, _1, 1.234); ... cout << obj(i) << endl; }
...Duane
Duane Murphy wrote:
The return type of boost::bind is fairly indeterminate. In order to call a bound function at a later time, look at boost::function. It does a nice job of holding on to a function that uses boost::bind.
I looked at "Using bind with Boost.Function" in the boost::function docs.
Mimicing that, for my example, I tried:
boost::function
I wish to store the return value of boost::bind in an intermediate object to invoke it at a later time. I only ever see examples which combine the call to boost:bind with the immediate invocation on the returned object such as:
#include
using namespace boost; #include <iostream> using namespace std; double f(int i, double d) { cout << "int = " << i << endl; return d; }
main() { int i = 99; cout << bind(f, _1, 1.234)(i) << endl; }
Instead I'd like to postpone the call to the returned object. What's the type of obj?
main() { int i = 99; WHAT_IS_MY_TYPE obj = bind(f, _1, 1.234); ... cout << obj(i) << endl; }
Cheenu Srinivasan wrote:
Duane Murphy wrote:
The return type of boost::bind is fairly indeterminate. In order to call a bound function at a later time, look at boost::function. It does a nice job of holding on to a function that uses boost::bind.
I looked at "Using bind with Boost.Function" in the boost::function docs. Mimicing that, for my example, I tried:
boost::function
bound_func = boost::bind(f, _1, 1.234); int i = 99; cout << bound_func(i) << endl; but it throws a bad_function_call exception when bound_func(i) is invoked. How do I use boost::function for this situation?
Works for me; it's probably a compiler bug. Which compiler are you using?
Try
boost::function
Cheenu Srinivasan wrote:
Instead I'd like to postpone the call to the returned object. What's the type of obj?
main() { int i = 99; WHAT_IS_MY_TYPE obj = bind(f, _1, 1.234); ... cout << obj(i) << endl; }
You can use a separate function template: template<class F> void test(F f) { int i = 99; std::cout << f(i) << std::endl; } int main() { test( boost::bind(f, _1, 1.234) ); }
participants (3)
-
Cheenu Srinivasan
-
Duane Murphy
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Peter Dimov