TRetainedRef

TRetainedRef<T>

A helper class which replaces T& as a function parameter when the reference is intended to be retained by the function (e.g. as a class member). The benefit of this class is that it is a compile error to pass an rvalue which might otherwise bind to a const reference, which is dangerous when the reference is retained.

Example:

struct FRaiiType { explicit FRaiiType(const FThing& InThing) : Ref(InThing) { }

void DoSomething() { Ref.Something(); }

FThing& Ref; };

void Test() { FThing Thing(...); FRaiiType Raii1(Thing); // Compiles Raii.DoSomething(); // Fine

FRaiiType Raii2(FThing(...)); // Compiles Raii.DoSomething(); // Illegal - reference has expired! }

But if the constructor is changed to use TRetainedRef then it fixes that problem:

struct FRaiiType { explicit FRaiiType(TRetainedRef<const FThing> InThing) : Ref(InThing) { }

FThing Thing(...); FRaiiType Raii1(Thing); // Compiles Raii.DoSomething(); // Fine

FRaiiType Raii2(FThing(...)); // Compile error! Raii.DoSomething();