Hey,
just wanted to know whether something like this would be possible sowmehow:

struct S
{
int m;
int n;
this(this)
{
m = void;
n = n;
}
}

So not the whole struct is moved everytime f.e. a function is called, but only n has to be "filled"

On Sunday, 30 July 2017 at 19:22:07 UTC, Jiyan wrote:
> Hey,
> just wanted to know whether something like this would be possible sowmehow:
>
> struct S
> {
> int m;
> int n;
> this(this)
> {
> m = void;
> n = n;
> }
> }
>
> So not the whole struct is moved everytime f.e. a function is called, but only n has to be "filled"

this(this) is called after the struct is copied. Doing something in the postblit constructor is too late. The second thing is that the struct is copied with memcpy. What you propose would require 2 memcpy calls to copy the first part of the struct and then the second part. Besides it is difficult to implement, it may reduce the performance of the copying since memcpy is optimized to copy memory chunks.

On Sunday, 30 July 2017 at 19:32:48 UTC, Eugene Wissner wrote:
> On Sunday, 30 July 2017 at 19:22:07 UTC, Jiyan wrote:
>> Hey,
>> just wanted to know whether something like this would be possible sowmehow:
>>
>> struct S
>> {
>> int m;
>> int n;
>> this(this)
>> {
>> m = void;
>> n = n;
>> }
>> }
>>
>> So not the whole struct is moved everytime f.e. a function is called, but only n has to be "filled"
>
> this(this) is called after the struct is copied. Doing something in the postblit constructor is too late. The second thing is that the struct is copied with memcpy. What you propose would require 2 memcpy calls to copy the first part of the struct and then the second part. Besides it is difficult to implement, it may reduce the performance of the copying since memcpy is optimized to copy memory chunks.

Ok thank you :)

On Sunday, 30 July 2017 at 19:22:07 UTC, Jiyan wrote:
> Hey,
> just wanted to know whether something like this would be possible sowmehow:
>
> struct S
> {
> int m;
> int n;
> this(this)
> {
> m = void;
> n = n;
> }
> }
>
> So not the whole struct is moved everytime f.e. a function is called, but only n has to be "filled"

I'll assume you mean copying (as per the title) not moving (because moving doesn't make sense to me in this context); use a dedicated method:

struct S
{
    int m, n;
    S sparseDup()
    {
        S obj;
        obj.n = n;
        return obj;
    }
}