Going by the suggested solution of using Atomic Reference Counters (std::arc)
for sharing immutable data across different tasks, I would presume that the
most generic solution would be to use the arc module. You can see an example of
this in action here :
https://github.com/smadhueagle/rustlings/blob/master/borrow.rs
Madhu
From: hata...@gmail.com
Date: Sat, 1 Jun 2013 22:30:35 -0700
To: abhijeet.ga...@gmail.com
CC: rust-dev@mozilla.org
Subject: Re: [rust-dev] Mutability and borrowing
True. I suppose I meant generic and memory efficient at the same time. I guess
it shouldn't be too much of a hassle to implement the specialized case of this
function if memory is absolutely critical.
Thanks
--
Ziad
On Sat, Jun 1, 2013 at 10:03 PM, Abhijeet Gaiha <abhijeet.ga...@gmail.com>
wrote:
The 'copy' parameter is the most generic way for the client to
handle this situation.
-- Abhijeet Gaihahttp://about.me/abhijeet.gaiha
On Sunday, 2 June 2013 at 10:32 AM, Ziad Hatahet wrote:
Thanks everyone. I actually thought about the two
suggestions before posting. I thought there might be some common paradigm for
this in the language though.
So I take it that implementing a += operator overload function would not have a
generic way to handle the case where the same parameter is passed on both sides?
--
Ziad
On Sat, Jun 1, 2013 at 9:42 PM, Tim Chevalier <catamorph...@gmail.com> wrote:
On Sat, Jun 1, 2013 at 9:33 PM, Ziad Hatahet <hata...@gmail.com> wrote:
> I have the following function:
>
> fn add_equal(x: &mut Complex, y: &Complex) {
> x.real += y.real;
> x.imag += y.imag;
> }
>
> Calling the function with the same variable being passed to both arguments
> (i.e. add_equal(&mut c, &c)), results in the compile error:
>
> error: cannot borrow `c` as immutable because it is also borrowed as mutable
>
> I am guessing this is to avoid aliasing issues? What is the way around this?
>
You can copy y instead of passing a reference to it:
fn add_equal(x: &mut Complex, y: Complex) { ...
Of course, that means that at the call site, you will have to write
something like add_equal(&mut c, copy c).
Unless you want to write a function that just takes one argument and
doubles it, like Abhijeet suggested, I don't know of another way
around this.
Cheers,
Tim
--
Tim Chevalier * http://catamorphism.org/ * Often in error, never in doubt
"Not a riot, it's a rebellion." -- Boots Riley
"Attention Bros and Trolls: When I call out your spew, I'm not angry,
I'm defiant." -- Reg Braithwaite
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