`this` as function attribute

[Timon Gehr]

On 6/4/22 18:57, Loara wrote:
> In D attributes that can be associated to functions can be divided into 
> two groups:
> 
> - attributes referring the function itself;
> - attributes referring the implicit `this` function parameter,
> 
> so attributes like `pure`, `@safe`, `ref`, ... belong to the first group 
> and `const`, `shared`, `scope` to the second one.
> 
> Maybe in the future would be necessary to apply the same attribute to 
> the member function or the `this` attribute (or both) that forces you to 
> reserve an additional attribute name in order to distinguish them.
> 
> Another approach is to use the `this` keyword in order to specify that 
> the passed attributes refers to the implicit `this` parameter instead of 
> the function member:
> 
> ```d
> class MyClass{
> ...
> void myfun() @A @B this( @A @C ) {
> ...
> }
> ...
> }
> ```
> In this example function `myfun` has the attributes `@A`, `@B` whereas 
> the `this` parameter has only `@A`, `@C` attributes.
> 
> In order to avoid backward incompatibility the `this` syntax won't be 
> necessary for all the attributes that can be associated to function 
> parameters but don't have sense for pure functions like `const`, 
> `immutable`...

Just put it in the argument list:

```d
void myfun(@A @C MyClass this, ...) @A @B { }
```