In the D Cookbook it has as part of the FibonacciRange example:

@property FibonacciRange save() { return this; }

And in the description it says:

"...save, which returns a new range that is a copy of the current range and can be advanced independently..."

Why is this a *copy*? (For a copy (in C++) I'd have expected return *this.)

On Thursday, 30 January 2020 at 10:31:08 UTC, mark wrote:
> In the D Cookbook it has as part of the FibonacciRange example:
>
> @property FibonacciRange save() { return this; }
>
> And in the description it says:
>
> "...save, which returns a new range that is a copy of the current range and can be advanced independently..."
>
> Why is this a *copy*? (For a copy (in C++) I'd have expected return *this.)

Oh, I understand now...

Sorry for the noise but I don't know how to delete a premature post!

(I'll answer here anyway just in case someone lands here via a web search.)

On Thursday, 30 January 2020 at 10:31:08 UTC, mark wrote:
> Why is this a *copy*? (For a copy (in C++) I'd have expected return *this.)

In C++, `this` is a pointer, but in D, it is a reference. So assignment follows those semantics instead; `Foo a = this` does a copy assignment and if you want a pointer, you need to explicitly ask for one with the & operator: `Foo* a = &this;`

fun fact, old versions of D, ~11ish years ago, actually worked the same way as C++. But the reference one was generally nicer and you can turn it back to the pointer as needed so it got changed.