On Tuesday, 28 December 2021 at 00:13:13 UTC, data pulverizer
wrote:
The types I'm generating are a template type I've constructed
for R's SEXP, so that my wrapped numeric vector (struct) type
is denoted `RVector!(REALSXP)`. But `alias REALSXP =
SEXPTYPE.REALSXP` where `SEXPTYPE` is an `enum`.
So if I start using `T.stringof` where `T =
RVector!(SEXPTYPE.REALSXP)` to generate code it starts to
create chaos because `T.stringof = "RVector!SEXPTYPE.REALSXP"`,
so if I'm trying to convert or instantiate a type using
`T.stringof ~ "(x)"`, I'll get `RVector!SEXPTYPE.REALSXP(x)`
which gives an error, and various types like this can occur
many times in a script. The new template allows me to safely
paste the type and get what I want
`RVector!(SEXPTYPE.REALSXP)(x)`.
The correct answer here is, "don't use `T.stringof` to generate
code."
The result of `.stringof` is completely implementation-defined,
may change arbitrarily between compiler releases, and is not even
guaranteed to be valid D code in the first place. You should not
rely on it unless you have literally no other choice.
In this case, the simplest solution is to have your code
generator accept a string as its input, rather than a type. For
example:
```d
enum instantiate(string type, string expr) = type ~ "(" ~ expr ~
")";
pragma(msg, instantiate!("RVector!(SEXPTYPE.REALSXP)", "x"));
```
