C++ Keywords - auto
Be precise with use of auto. Knowing that things are constant or that indirections are occurring is very valuable information to readers.
auto/const autoauto&/const auto&: a reference to non-const / constauto*/const auto*: when the type is a pointer.
auto For returned unique_ptr
If GetFoo returns unique_ptr<Foo>:
These 2 are equivalent:
const auto foo = GetFoo();(Preferred)const auto& foo = GetFoo();
This does not compile.
const auto* foo = GetFoo();
auto* x = y expects that y is a C++ pointer. But std::unique_ptr<T> is just an object that behaves like a pointer and takes care of ownership. Other than that, it is just a regular C++ class, not a regular pointer, like int*.
Do not do:
const auto* foo = GetFoo().get();
It destructs the pointer when the statement ends, leaving thing as a dangling pointer.
GetFoo will return a temporary object, you get the pointer to the underlying Foo* and assign it to foo. However as soon as that line is execute, the temporary unique_ptr will be destroyed and the underlying Foo object is freed, so now foo is a dangling pointer to the freed memory.