Re: What happened to the "mutable struct" debate?

Timo Kinnunen timo.kinnunen at
Fri Jan 23 16:08:10 UTC 2015

Pass-by-ref is easily emulated by boxing a mutable struct and then operating on the boxed struct.

Have a nice day,

Sent from Windows Mail

From: Vitaly Davidovich
Sent: ‎Friday‎, ‎January‎ ‎23‎, ‎2015 ‎17‎:‎00
To: Rezaei, Mohammad A.
Cc: valhalla-dev at

If mutable structs are not allowed to be passed by ref, then one is more
likely to lose writes as the struct is passed through a method chain.
There's no *necessity* per say, but the danger zone is expanded.

The by-ref would be useful for immutable structs as well when you want to
avoid copying costs for a largish struct.

On Fri, Jan 23, 2015 at 10:54 AM, Rezaei, Mohammad A. <
Mohammad.Rezaei at> wrote:

> >Very much so.  This is indeed Big Strike #1 against them; this is a new
> >big complexity that Java (platform and developers) have not had to deal
> >with.
> >
> I don't really see why mutable structs would necessitate pass by
> reference. Java developers are used to pass by value semantics and there is
> a well-known, but admittedly ugly pattern for pass by reference (use an
> array or mutable wrapper).
> The reference question comes up even in all-final value types. But I'll
> pose that question in a separate thread.
> Thanks
> Moh

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