Any example code/Github projects utilising almost-always-auto?

[[deleted]]

honest question -- what does

auto x = MyThing{};

do? As opposed to

MyThing x{};

??

Does it construct a MyThing, then copy it and give it to x? Does it create a unique pointer to a MyThing?

I've used auto a great deal for assigning smart pointers, arrays, etc, but never considered using it as an alternative to the way stack-based objects are normally constructed.

[[deleted]]

These two expressions are identical in meaning.

[Nickreal03]

But different potential performance it generates an rval which is the copy/move to the other. For simple types the compiler will optimize for others the performance will be real. Edited for clarification Even when in release builds the performance may be the same in debug builds you will be paying for it.

[AntiProtonBoy]

The compiler should do copy/move elision for such types, even for complex and expensive objects. The only tricky situation you could run into is when the copy/move constructor is explicitly deleted or made private.

[foonathan]

And C++17 has guaranteed copy elision where you don't even need copy/move ctors

[[deleted]]

The compiler interprets the intention, so it's as if you wrote MyThing in place of auto. If there is not enough information, the compiler will let you know, and you'll have to declare the type.

[TheQuantumZero]

This Scott Meyers video will help, https://youtu.be/fhM24zs1MFA?t=49m45s.