Re: Allocating a slice object
Am Thu, 04 Jul 2013 15:54:48 +0200 schrieb monarch_dodra monarchdo...@gmail.com: This should work: int[] *pSlice = (new int[][1]).ptr; -Steve Hum... That would allocate a dynamic array of slices though right? There'd be the Appendable overhead for just one element... No, it allocates a static one-element array of int[]s and then returns the pointer to the first and only element. It's similar to wrapping it in a struct. So +1 for that solution. -- Marco
Re: Allocating a slice object
On Monday, 8 July 2013 at 15:43:21 UTC, Marco Leise wrote:
Am Thu, 04 Jul 2013 15:54:48 +0200
schrieb monarch_dodra monarchdo...@gmail.com:
This should work:
int[] *pSlice = (new int[][1]).ptr;
-Steve
Hum... That would allocate a dynamic array of slices though
right? There'd be the Appendable overhead for just one
element...
No, it allocates a static one-element array of int[]s and then
returns the pointer to the first and only element. It's
similar to wrapping it in a struct. So +1 for that solution.
I don't think that allocates a static array, it's just an
alternative syntax for dynamic array allocation. The fact that
you are extracting a pointer from it and it only has a single
element doesn't mean it is a static array.
//
void main()
{
int[]* pSlice = (new int[][4]).ptr;
writeln(pSlice[0 .. 4].capacity);
}
//
This prints 7 for me, which would simply be impossible for new
was allocating a static array.
Allocating a slice object
This is a pretty stupid question, but how would you allocate an
int[] on the heap? I'm not talking about the array, but the
actual slice object. EG:
int[]* pSlice = new int[];
//Error: new can only create structs,
//dynamic arrays or class objects, not int[]'s
Is there a simple idiomatic way?
I'm currently doing it by allocating a struct that wraps one:
struct S{int[] a;}
int[]* pSlice1 = cast(int[]*) new S;
int[]* pSlice2 = (new S).a;
Note: This is also a neat way to allocate a static array on the
heap.
Anybody have some better way?
Re: Allocating a slice object
On Thursday, 4 July 2013 at 12:02:16 UTC, monarch_dodra wrote:
This is a pretty stupid question, but how would you allocate an
int[] on the heap? I'm not talking about the array, but the
actual slice object. EG:
int[]* pSlice = new int[];
//Error: new can only create structs,
//dynamic arrays or class objects, not int[]'s
Is there a simple idiomatic way?
I'm currently doing it by allocating a struct that wraps one:
struct S{int[] a;}
int[]* pSlice1 = cast(int[]*) new S;
int[]* pSlice2 = (new S).a;
Note: This is also a neat way to allocate a static array on the
heap.
Yes. This is a good example of how D type system and memory
allocation type are different, despite many move type system
terms into memory category.
Anybody have some better way?
Another way:
import std.stdio;
void main()
{
int[] arr;
auto x = { return arr; } ;
writeln(arr);
}
Re: Allocating a slice object
On Thu, 04 Jul 2013 08:02:13 -0400, monarch_dodra monarchdo...@gmail.com
wrote:
This is a pretty stupid question, but how would you allocate an int[]
on the heap? I'm not talking about the array, but the actual slice
object. EG:
int[]* pSlice = new int[];
//Error: new can only create structs,
//dynamic arrays or class objects, not int[]'s
Is there a simple idiomatic way?
Not really. There was talk at one point of deprecating that version, so
you had to do new int[](5) instead of new int[5], and then using new
int[5] to mean new fixed sized array of size 5 on the heap, and then new
int[] would mean new slice on the heap.
But I think there's a real lack of benefit to this, plus it would be
confusing to people familiar with other languages.
I'm currently doing it by allocating a struct that wraps one:
struct S{int[] a;}
int[]* pSlice1 = cast(int[]*) new S;
int[]* pSlice2 = (new S).a;
Note: This is also a neat way to allocate a static array on the heap.
Anybody have some better way?
This should work:
int[] *pSlice = (new int[][1]).ptr;
-Steve
Re: Allocating a slice object
On Thursday, 4 July 2013 at 13:37:52 UTC, Steven Schveighoffer
wrote:
On Thu, 04 Jul 2013 08:02:13 -0400, monarch_dodra
monarchdo...@gmail.com wrote:
This is a pretty stupid question, but how would you allocate
an int[] on the heap? I'm not talking about the array, but
the actual slice object. EG:
int[]* pSlice = new int[];
//Error: new can only create structs,
//dynamic arrays or class objects, not int[]'s
Is there a simple idiomatic way?
Not really. There was talk at one point of deprecating that
version, so you had to do new int[](5) instead of new int[5],
and then using new int[5] to mean new fixed sized array of
size 5 on the heap, and then new int[] would mean new slice on
the heap.
But I think there's a real lack of benefit to this, plus it
would be confusing to people familiar with other languages.
One advantage I see is that it is a way to allocate a fixed
amount of objects in memory in heap, without having to add the
Appendable info.
But that change would require changing an existing semantic, so
fat chances of that happening now.
I'm currently doing it by allocating a struct that wraps one:
struct S{int[] a;}
int[]* pSlice1 = cast(int[]*) new S;
int[]* pSlice2 = (new S).a;
Note: This is also a neat way to allocate a static array on
the heap.
Anybody have some better way?
This should work:
int[] *pSlice = (new int[][1]).ptr;
-Steve
Hum... That would allocate a dynamic array of slices though
right? There'd be the Appendable overhead for just one element...
