Why callers should explicitly document storage classes

[Vladimir Panteleev]

On Sun, 14 Aug 2011 14:34:46 +0300, Mehrdad <wfunction at hotmail.com> wrote:

> Consider this example:
>
>      // In module foo.d:
>      void baz(bool condition, lazy int value)
>      {
>          if (condition)
>              writeln(value);
>      }
>
>      // In module bar.d:
>      import foo;
>      bool someCondition() { return false; }
>      void main()
>      {
>          auto vals = [1, 2, 3, 4];
>          while (!vals.empty)
>              baz(someCondition(), items.moveFront());
>      }
>
> There is **absolutely NO WAY** to figure out what's wrong at the calling  
> site. You need to check /every/ method call and make sure nothing weird  
> is happening (e.g. lazy), and it's pretty much impossible to figure it  
> out unless you're intimately familiar with the entire library you're  
> calling -- something which (obviously) doesn't scale.
>
> I don't know of a similar example off the top of my head for out/ref,  
> but the same idea applies.
>
> Is this convincing enough that we need to document storage classes at  
> the CALLING site, rather than just the CALLEE site?

I've raised this issue during voting for std.parallelism. I think the  
consensus was that "lazy" before lazy arguments would be appropriate, but  
"ref" would be mostly pointless, due to complex and reference types.

-- 
Best regards,
  Vladimir                            mailto:vladimir at thecybershadow.net