• %u (12/12) Jun 26 2011 hi
• simendsjo (4/16) Jun 26 2011 The runtime will duplicate array2 to avoid array stomping. Steven
• Steven Schveigoffer (4/26) Jun 26 2011 This can happen, but in this case, the two slices in fact point at the s...

%u <asmasm hotmail.com> writes:

hi
I create two arrays and I want the change in one of them effects the other one.

i try

int[] array1 = [1, 2, 3, 4, 5];
int[] array2;
array2 = array1; // without .dup

assert(array1 == array2);
assert(array1 is array2); // here i am confused because 'is' mean thay have
the same address or what?

array2 ~= 6;
assert(array1 == [1, 2, 3, 4, 5]); // here is the problem
assert(array2 == [1, 2, 3, 4, 5, 6]);

simendsjo <simen.endsjo pandavre.com> writes:

On 26.06.2011 13:59, %u wrote:
 hi
 I create two arrays and I want the change in one of them effects the other one.

 i try

 int[] array1 = [1, 2, 3, 4, 5];
 int[] array2;
 array2 = array1; // without .dup

 assert(array1 == array2);
 assert(array1 is array2); // here i am confused because 'is' mean thay have
 the same address or what?

 array2 ~= 6;
 assert(array1 == [1, 2, 3, 4, 5]); // here is the problem
 assert(array2 == [1, 2, 3, 4, 5, 6]);

The runtime will duplicate array2 to avoid array stomping. Steven 
Schveighoffer wrote a nice article on arrays you should read: 
http://www.dsource.org/projects/dcollections/wiki/ArrayArticle

Steven Schveigoffer <schveiguy yahoo.com> writes:

simendsjo Wrote:

 On 26.06.2011 13:59, %u wrote:
 hi
 I create two arrays and I want the change in one of them effects the other one.

 i try

 int[] array1 = [1, 2, 3, 4, 5];
 int[] array2;
 array2 = array1; // without .dup

 assert(array1 == array2);
 assert(array1 is array2); // here i am confused because 'is' mean thay have
 the same address or what?

 array2 ~= 6;
 assert(array1 == [1, 2, 3, 4, 5]); // here is the problem
 assert(array2 == [1, 2, 3, 4, 5, 6]);

 
 The runtime will duplicate array2 to avoid array stomping. Steven 
 Schveighoffer wrote a nice article on arrays you should read: 
 http://www.dsource.org/projects/dcollections/wiki/ArrayArticle

This can happen, but in this case, the two slices in fact point at the same
data.

The issue here is that the user is expecting the slice type to have full
reference semantics. The slice type has its own length -- they do not share the
length. So making one longer (by appending in this case) does not change the
length of the other.it is a common misconception from people who come from
languages that have a full reference array type.

-Steve