Re: [julia-users] Re: Understanding immutables

[Cedric St-Jean]

On Sun, Feb 7, 2016 at 10:11 AM, Bart Janssens  wrote:

>
> On Sunday, February 7, 2016 at 3:39:51 PM UTC+1, Cedric St-Jean wrote:
>
>> then `a` is stack-allocated. The foo(a) call may either copy `a` further,
>> or just pass on a stack pointer to the existing `a`, depending on compiler
>> details. Any stack-allocated object gets automatically wiped as the stack
>> unwinds, hence does not need GC'ing.
>>
>>
> I think that in this case "a" is heap-allocated, since ImagePos is not a
> bits type.
>

I don't think this necessarily follows. Inside ImagePos, there is a pointer
to an Image, which is why it's not a bits type, but that doesn't preclude
stack allocation in general.


> You can check this with isbits(). Just today, I found the following post
> that explains this at length:
> http://julialang.org/blog/2013/03/efficient-aggregates/
>
> Cheers,
>
> Bart
>

[julia-users] Re: Understanding immutables

[Bart Janssens]

On Sunday, February 7, 2016 at 3:39:51 PM UTC+1, Cedric St-Jean wrote:

> then `a` is stack-allocated. The foo(a) call may either copy `a` further, 
> or just pass on a stack pointer to the existing `a`, depending on compiler 
> details. Any stack-allocated object gets automatically wiped as the stack 
> unwinds, hence does not need GC'ing.
>
>
I think that in this case "a" is heap-allocated, since ImagePos is not a 
bits type. You can check this with isbits(). Just today, I found the 
following post that explains this at length:
http://julialang.org/blog/2013/03/efficient-aggregates/

Cheers,

Bart