(C++) std::bind2nd

 

std::bind2nd is deprecated [2]. The function template std::bind provides a better solution [2].

 

std::bind2nd is a binder to call a binary function with the value bound as second argument. If the first argument needs to be bound, use std::bind1st instead.

 

The distinction between std::bind1st and std::bind2nd gets clear in division:

• If on all elements, an element called x, you want to perform 'x / 2.0', use std::bind2nd on the 2.0. This is demonstrated in the function Halve, which is shown below in the example
• If on all elements, an element called x, you want to perform '1.0 / x', use std::bind1st one the 1.0. This is demonstrated in the function Reciprocal

 

 

 

 

 

---

#include <algorithm> #include <numeric> #include <vector> //From http://www.richelbilderbeek.nl/CppHalve.htm void Halve (std::vector<double>& v) {   std::transform(     v.begin(),v.end(),v.begin(),     std::bind2nd(std::divides<double>(),2.0)); }

 

 

 

 

 

Advice

 

• Prefer Lambda expressions over binders [1]

 

 

 

 

 

References

 

1. Scott Meyers. C++ And Beyond 2012 session: 'Initial thoughts on Effective C++11'. 2012. 'Prefer Lambdas over Binders'
2. Working Draft, Standard for Programming Language C++. 2014-08-22. N3936. Paragraph D.10. 'The binders binder1st, bind1st and bind2nd are deprecated [Note: the function template bind provides a better solution -end note]'