On Tuesday, 26 February 2013 at 16:28:59 UTC, Ivan Kazmenko wrote:
Hi!
I have recently experimented with ways to express the exact
instantiated type of a generic struct, and found that I can in
some cases use "this" as that type.
1) D allows omitting parameter names in function definitions
which are replaced by implicitly created _param_XXX.
2) This as a type in parameter list replaces type of this.
What you observe is consequence of combination of this rules. The
most unintuitive is that applying attribute to postblit
declaration makes it a regular constructor which takes argument
of that struct type.
And so I wonder:
(1) Should I refrain from using this as a type, is it a bug?
Better to avoid such usage.
(2) A matter of style: what is the idiomatic way to take the
exact type of a templated struct? For example, which method
signature to return a typeof(this) value is "better" in which
way if all have the same effect:
-----
struct S (A, B, C)
{
...
auto method () {...}
S method () {...}
S !(theA, theB, theC) method () {...}
typeof (this) method () {...}
}
-----
Note that S, theA, theB and theC can get lengthy.
You can use template this parameter in templates and avoid in
non-templates.
(3) Is the usage of unnamed parameters and _param_### a
language feature or an implementation-specific detail I should
not ever use?
-----
Ivan Kazmenko.
It is implementation-specific detail.
