If I want to write a function that operates on a struct

struct S { }

What are the differences between:

void(S* s)

void(ref S s)

Also, for my general knowledge, is there a way to set default function parameters, such as scope or lazy?

On Sunday, 29 December 2013 at 19:42:39 UTC, Jonathan wrote:
> If I want to write a function that operates on a struct
>
> struct S { }
>
> What are the differences between:
>
> void(S* s)

s is a pointer to an instance of S, in the raw C sense.

> void(ref S s)

s can be used as a normal S, but changes are visible to the caller. It can be imagined as a pointer behind the scenes.

>
> Also, for my general knowledge, is there a way to set default function parameters, such as scope or lazy?

I don't fully understand what you mean by this.

On Sunday, 29 December 2013 at 19:42:39 UTC, Jonathan wrote:
> If I want to write a function that operates on a struct
>
> struct S { }
>
> What are the differences between:
>
> void(S* s)
>
> void(ref S s)

You cannot set a default value (like null) for ref parameters, but you can for pointer.

On Sunday, 29 December 2013 at 21:47:52 UTC, Namespace wrote:
> On Sunday, 29 December 2013 at 19:42:39 UTC, Jonathan wrote:
>> If I want to write a function that operates on a struct
>>
>> struct S { }
>>
>> What are the differences between:
>>
>> void(S* s)
>>
>> void(ref S s)
>
> You cannot set a default value (like null) for ref parameters, but you can for pointer.

Well, a ref *can't* be null. In terms of default value, both can have them, in terms of referencing a static object though.

The only functional difference I know of in pass-by-ref vs pass-by-pointer is indeed the null pointer:
- Pass by pointer means you *can* pass a null (yay).
- But pass by ref means the implementation does not have to worry about null references (yay).

On Sunday, 29 December 2013 at 22:11:22 UTC, monarch_dodra wrote:
> On Sunday, 29 December 2013 at 21:47:52 UTC, Namespace wrote:
> Well, a ref *can't* be null. In terms of default value, both can have them, in terms of referencing a static object though.
>
> The only functional difference I know of in pass-by-ref vs pass-by-pointer is indeed the null pointer:
> - Pass by pointer means you *can* pass a null (yay).
> - But pass by ref means the implementation does not have to worry about null references (yay).

bool isNullRef(ref int i)
{
    return &i is null;
}
void main()
{
    int* np = null;
    assert(isNullRef(*np));
}