Template setters

Kamil Rojewski <kamil.rojewski@googlemail.com>
Sat, 7 Sep 2013 05:00:59 -0700 (PDT)
{ Reformatted; please limit your lines to 70 characters -mod }


Recently I was wondering about trying out a new approach to writing
setters in classes. Traditional pre-C++11 approach relied on passing
const & for complex types and value for simple ones, like int. That
didn't sit well with me, because:

1. It doesn't take advantage of modern C++11 features, like move
2. Introduces inconsistency.

So I began to wonder about passing universal references (as per Scott
Meyers' terminology) instead. With this approach all setters would
take the form of:

template<class T>
void setWidget(T &&widget)
     mWidget = std::forward<T>(widget);

This has some pros and cons:

+ Takes into account move semantics.
+ Allows utilization of any form of operator =.
+ Retains consistency across all types (const & vs. value arguments).

- Breaks encapsulation, as the definition needs to be visible.
- Moves possible type mismatch errors inside the setter, instead of
- Can lead to confusion, as the setter becomes a type sink (although
   the argument can be ruled out, since it propagates to operator =

In my opinion the advantages outweigh the disadvantages, although
moving the point of possible error is a strong one. That's why I'm yet
to decide if I should make this my standard practice. Any thoughts?

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