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Looking for new names in new callbacks schema [message #45985]

Tue, 09 February 2016 09:05

mirek
Messages: 14039
Registered: November 2005

Ultimate Member

I am now sort of refactoring Core to fully 'embrace' C++11. One of things that I decided needs update is Callbacks.

Current (U++2015) version supports lambdas fine, but as sort of 'external' addition. It is not quite effective, lambdas are stored through std::function indirectly, so invoking requires unnecessary pointer dereferencing.

While I plan to use a little bit more of std:: things, I came to conclusion that we need our std::function equivalent because

- std::function is not Moveable (but should be)
- std::function throws exception if it is empty and function is invoked, while more reasonable behaviour is NOP
- our version provides "combination" operator<< that combines several callables into one

Right now, I call this Upp::Function, but I do not quite like the name. I am considering Upp::Fn, Upp::Functor, Upp::Callable, Upp::Delegate ...

Next thing... Even if we have Upp::Function, we still need derived Callback and Gate. The fundamental reason for that is overloading resolution, std::function/Upp::function need to have "catch all" constructor to convert lambdas (which are always of "unknown" type), so using Function directly make impossible to e.g. have Ctrl::operator<<=.

Meanwhile, with C++11 template parameter packs (template varargs), it is relatively possible to avoid most of current callback/callback1/callback2... mess and define single class instead of Callback...Callback5. Unfortunately, this class cannot be just "Callback", because in parameterless form, it still needs an empty list of paramaters ("Callback<>") so it would be backward incompatible. (And yes, we still need to provide all those Callback[N] and callback[n] things for backward compatibility too).

So, so far I have named those new classes CallbackN and GateN, but I do not like these names either...

Any suggestions about how to name those new entities?

Mirek

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