DIP69 - Implement scope for escape proof references

[Daniel Murphy via Digitalmars-d]

"Walter Bright"  wrote in message news:m60oa4$kd5$1 at digitalmars.com...

> > I have std.simd sitting here, and I really want to finish it, but I
> > still don't have the tools to do so.
> > I need, at least, forceinline to complete it, but that one *is*
> > controversial - we've talked about this for years.
>
> I proposed a DIP to fix that, but it could not get reasonable consensus.
>
>    http://wiki.dlang.org/DIP56
>
> You did, after all, convince me that we need an "always inline" and a 
> "never inline" method.

>From the DIP:

> If a pragma specifies always inline, whether or not the target function(s) 
> are actually inlined is
> implementation defined, although the implementation will be expected to 
> inline it if practical.
> Implementations will likely vary in their ability to inline.

I expect a proposal in which 'always' means "inline or give an error" would 
be much better received.

> The thing is, I don't understand *why* you want to wrangle storage 
> classes. What is the coding pattern?

> That's the wrong question. I could ask "why do you hate ref as a storage 
> class"?

I suspect the answer is that sometimes it is useful to ensure some 
parameters are passed by reference, not by value.  With ref as a type, this 
would be trivial:

template MyParamType(T)
{
    static if (someCriteria!T)
        alias MyParamType = ref(T);
    else
        alias MyParamType = T;
}

void myFunction(T, U, V)(const MyParamType!T, const MyParamType!U, const 
MyParamType!V)
{
    ...
}