shared and getParameterStorageClasses bug?

[Petar]

On Tuesday, 25 August 2020 at 12:52:14 UTC, Jean-Louis Leroy 
wrote:
> On Tuesday, 25 August 2020 at 07:16:39 UTC, Petar Kirov 
> [ZombineDev] wrote:
>> Interesting, so essentially, you need a good solution for your 
>> refractParameter function, right? I'll try to check the code 
>> in more detail later and think about it.
>
> Actually it already works as is:
>
> void original(lazy const Object);
>
> enum edited =
>   refract!(original, "original")
>   .withName("copy")
>   .withParametersAt(0, Parameter("foo", "int"));
> mixin(edited.mixture);
>
> void expected(int, lazy const Object);
> static assert(is(typeof(&copy) == typeof(&expected)));
>
> The generated mixin is:
>
> pragma(msg, edited.mixture);
> // @system bolts.experimental.refraction.ReturnType!(original)
> // copy(int foo, lazy 
> bolts.experimental.refraction.Parameters!(original)[0] _0);
>
> (In this case, Parameters!(original)[0..1] (note the ..) would 
> have worked as well - and it would have looker better too. I'll 
> implement that soon.)
>
> Let's look at the function types:
>
> pragma(msg, typeof(&original).stringof); // void function(lazy 
> const(Object))
> pragma(msg, typeof(&copy).stringof);     // void function(int 
> foo, lazy const(Object) _0) @system

Nice!

> It looks like it is impossible to tell the difference between 
> 'const object' and 'const(Object)' - the substitution happens 
> too early. So I guess it doesn't matter...

Yes, `Q T` and `Q(T)` is exactly the same type (for Q ∈ { const, 
immutable, shared, inout } ), so you shouldn't try to 
differentiate between the two. (And `Q(T)` is the canonical 
notation.)

BTW, 2-3 years ago I played with a similar task (meta programming 
utility library), and one difference in the approach I took was 
to avoid thick abstractions. In some cases, this works well, 
though since I didn't have use cases involving heavy function 
type processing recently I didn't push much in that direction.

You can find some of the code here: 
https://gist.github.com/PetarKirov/a808c94857de84858accfb094c19bf77#file-rxd-meta2-d-L65-L123