Click here to Skip to main content
11,929,249 members (54,382 online)
Rate this:
Please Sign up or sign in to vote.
See more: C++ C++11 Lambda
I want to do something like this

template <typename T, typename IncrementorT = [] (T& val) -> T& {val++; return val;} >
class RangeAllocator...

where IncrementorT is a user replaceable functor that RangeAllocator will use to increment values. I know I can do it using a struct but I'm interested to play with the new c++11 toys.
Posted 30-Apr-13 21:48pm
Maximilien 1-May-13 8:23am
Dear mother of god!!!
Volynsky Alex 1-May-13 10:01am
Let's read the following post:
jsolutions_uk 1-May-13 10:11am
just beat me to it :)
Volynsky Alex 1-May-13 11:17am
Rate this: bad
Please Sign up or sign in to vote.

Solution 1

I'm not sure it is possible with lambdas, it's looking rather like a polymorphic lambda. check here[^]. I just don't think lambdas were intended to be used in the context of template based generic programming.

The closest I have managed to get to implementing what you have above is this:

template <typename T>
T& func(T& val)
    return val;
template <typename T, T&(*Func)(T&) = func<T>>
class SomeClass
    SomeClass() : val(0) {};
    void CallIt()
        std::cout << "val before call = " << val << std::endl;
        std::cout << "val after call = " << val << std::endl;
    T val;  
int main(int argc, char* argv[])
    SomeClass<int> instance;
	return 0;

But then that doesn't help with your original question wrt playing around with lambdas, and it is also probably just as simple to use a functor in my particular example.

I'd love to here if someone managed to do this, or by using std::function as a wrapper for a lambda.
Rate this: bad
Please Sign up or sign in to vote.

Solution 2

I know you can use functions as template parameters[^]. I suppose it could work with lambdas, but I have not tried myself.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

  Print Answers RSS
Top Experts
Last 24hrsThis month

Advertise | Privacy | Mobile
Web01 | 2.8.151126.1 | Last Updated 2 May 2013
Copyright © CodeProject, 1999-2015
All Rights Reserved. Terms of Service
Layout: fixed | fluid

CodeProject, 503-250 Ferrand Drive Toronto Ontario, M3C 3G8 Canada +1 416-849-8900 x 100