It looks like http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-closed.html#526 addressed this problem (or something very similar to it) as a potential defect in the standard: 1) Parameters taken by const reference can be changed during execution of the function Examples: Given std::vector v: v.insert(v.begin(), v[2]); v[2] can be changed by moving elements of vector The proposed resolution was that this … Read more
std::reference_wrapper is useful in combination with templates. It wraps an object by storing a pointer to it, allowing for reassignment and copy while mimicking its usual semantics. It also instructs certain library templates to store references instead of objects. Consider the algorithms in the STL which copy functors: You can avoid that copy by simply … Read more
This question was the subject of my blog on June 23rd 2011. Thanks for the great question! The C# team is considering this for C# 7. See https://github.com/dotnet/roslyn/issues/5233 for details. UPDATE: The feature made it in to C# 7! You are correct; .NET does support methods that return managed references to variables. .NET also supports … Read more
Let’s look at the signature for into_bytes: fn into_bytes(self) -> Vec<u8> This takes self, not a reference to self (&self). That means that self will be consumed and won’t be available after the call. In its place, you get a Vec<u8>. The prefix into_ is a common way of denoting methods like this. I don’t … Read more
Your function expects a reference to an actual string pointer in the calling scope, not an anonymous string pointer. Thus: string s; string* _s = &s; myfunc(_s); should compile just fine. However, this is only useful if you intend to modify the pointer you pass to the function. If you intend to modify the string … Read more
My own rule of thumb : Use a reference member when you want the life of your object to be dependent on the life of other objects : it’s an explicit way to say that you don’t allow the object to be alive without a valid instance of another class – because of no assignment … Read more
Java is confusing because everything is passed by value. However for a parameter of reference type (i.e. not a parameter of primitive type) it is the reference itself which is passed by value, hence it appears to be pass-by-reference (and people often claim that it is). This is not the case, as shown by the … Read more
After the first foreach loop, $item is still a reference to some value which is also being used by $arr[2]. So each foreach call in the second loop, which does not call by reference, replaces that value, and thus $arr[2], with the new value. So loop 1, the value and $arr[2] become $arr[0], which is … Read more
Return values are almost always the right choice when the method doesn’t have anything else to return. (In fact, I can’t think of any cases where I’d ever want a void method with an out parameter, if I had the choice. C# 7’s Deconstruct methods for language-supported deconstruction acts as a very, very rare exception … Read more
Check to make sure that your project isn’t set up to use the .NET Framework 4 Client Profile. You can check/change this by right-clicking your project (not the solution), select Properties -> Application -> Target framework. The target framework is a dropdown on that page. This is a problem in Visual Studio (I would even … Read more