Re: Struct Postblit Void Initialization

[Moritz Maxeiner via Digitalmars-d-learn]

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;
}
}

Re: Struct Postblit Void Initialization

[Jiyan via Digitalmars-d-learn]

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 :)

Re: Struct Postblit Void Initialization

[Eugene Wissner via Digitalmars-d-learn]

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.

Struct Postblit Void Initialization

[Jiyan via Digitalmars-d-learn]

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"