The spec for array says:
	Static arrays are value types. Unlike in C and D version 1, static arrays are passed to functions by value. Static arrays can also be returned by functions.

I don't get the "static arrays are passed to functions by value" part.

Here I am passing in a static and dynamic array. Both are passed by value, and the function can modify the array of both

	{
		void func(int[] arr, void* ptr) {
			arr[0] = 9;
			assert(&arr != ptr);
		}

		int[3] a = [1,2,3];
		func(a, &a);
		assert(a == [9,2,3]); // changed..
		
		int[] b = [1,2,3];
		func(b, &b);
		assert(b == [9,2,3]);
	}

On 2010-08-07 9:26, simendsjo wrote:
> The spec for array says:
> Static arrays are value types. Unlike in C and D version 1, static
> arrays are passed to functions by value. Static arrays can also be
> returned by functions.
>
> I don't get the "static arrays are passed to functions by value" part.
>
> Here I am passing in a static and dynamic array. Both are passed by
> value, and the function can modify the array of both
>
> {
> void func(int[] arr, void* ptr) {
> arr[0] = 9;
> assert(&arr != ptr);
> }
>
> int[3] a = [1,2,3];
> func(a, &a);
> assert(a == [9,2,3]); // changed..
>
> int[] b = [1,2,3];
> func(b, &b);
> assert(b == [9,2,3]);
> }

When you use "int[]" as the parameter type, the array is passed by reference as a slice of the original array. If you write the function like this:

fund(int[3] arr, void* ptr) {...}

Now the array is passed by value and a copy is made.

simendsjo <simen.endsjo@pandavre.com> wrote:

> The spec for array says:
> 	Static arrays are value types. Unlike in C and D version 1, static arrays are passed to functions by value. Static arrays can also be returned by functions.
>
> I don't get the "static arrays are passed to functions by value" part.
>
> Here I am passing in a static and dynamic array. Both are passed by value, and the function can modify the array of both
>
> 	{
> 		void func(int[] arr, void* ptr) {
The problem is here    ^^

What your function signature is saying, is 'pass arr to me as if a
dynamic array'. If you want to pass a static array, define the function
like this, and you will see magic at work:
    void func( int[3] arr, void* ptr ) {

> 			arr[0] = 9;
> 			assert(&arr != ptr);
> 		}
>
> 		int[3] a = [1,2,3];
> 		func(a, &a);

This call is equivalent to func( a[], &a );. Since your function says
to treat the array as dynamic, a slice is created from your static array.

> 		assert(a == [9,2,3]); // changed..
> 		
> 		int[] b = [1,2,3];
> 		func(b, &b);
> 		assert(b == [9,2,3]);
> 	}


-- 
Simen

Hello simendsjo,

> The spec for array says:
> Static arrays are value types. Unlike in C and D version 1, static
> arrays are passed to functions by value. Static arrays can also be
> returned by functions.
> 
> I don't get the "static arrays are passed to functions by value" part.
> 
> Here I am passing in a static and dynamic array. Both are passed by
> value, and the function can modify the array of both

What that is saying is that "if the type of the function arg is a static array..." not "if the value passed to the function is a static array..."

An example of a function taking a static array is:

void Fn(int[5] arr){ ... }

-- 
... <IXOYE><

On 08.08.2010 01:52, BCS wrote:
> What that is saying is that "if the type of the function arg is a static
> array..." not "if the value passed to the function is a static array..."

Yes, it would help to read the spec a bit closer :)