byKeyValue is not available at compilation-time right ?

[jfondren]

On Sunday, 25 July 2021 at 05:10:32 UTC, someone wrote:
> /// implementation: however, would it be possible to 
> dynamically‐load the following enums from a file at 
> compilation‐time ?
>
> public immutable enum structureLocations = [
>    r"BUE"d : typeLocation(r"arg"d, r"Buenos Aires"d, r"ART"d),
>    r"GRU"d : typeLocation(r"bra"d, r"São Paulo"d, r"BRT"d),
>    r"HHN"d : typeLocation(r"deu"d, r"Frankfurt am Main"d, 
> r"CET"d),
>    r"LHR"d : typeLocation(r"gbr"d, r"London"d, r"UTC"d),
>    r"NYC"d : typeLocation(r"usa"d, r"New York"d, r"EST"d)
>    ];

```
Error: `_aaRange` cannot be interpreted at compile time, because 
it has no available source code
```

Yep, seems that's not available.

What you're doing with `immutable enum structureLocations` is 
creating a manifest constant, i.e. your AA initialization is 
copy-pasted into each use of it, which means your program is 
rebuilding this AA at runtime every time it comes up. You 
probably got to this point as a bare `immutable 
structureLocations` errored out to the non-constant expression.

You should be able to use a shared static module initializer to 
initialize an immutable AA, 
https://dlang.org/spec/module.html#staticorder , but although 
I've seen examples of simple string[string] initialization, it 
seems to be very hard to get more complex AAs past the 
std.array/std.exception tools.

So here's something you can do:

```d
__gshared const dstring[][dstring] structureExchanges;
__gshared const dstring[dstring] exchangeStructures;

shared static this() {
     import std.string, std.algorithm;

     dstring[][dstring] exchanges;
     // could easily load this from a file
     "   B3: B3 formerly Bolsa de Valores de São Paulo (aka 
BOVESPA)
         BCBA: Bolsa de Comercio de Buenos Aires
         LSE: London Stock Exchange
         NASDAQ: National Association of Securities Dealers 
Automated Quotations
         NYSE: New York Stock Exchange
         XETRA: Deutsche Börse
     "d.strip.splitLines.map!strip.each!((dstring exch) {
         const pair = exch.split(": ");
         exchanges[pair[0]] = [pair[1], "some other values"d];
     });
     structureExchanges = exchanges;

     dstring[dstring] structures;
     foreach (k, v; exchanges)
         structures[v[0]] = k;
     exchangeStructures = structures;
}
```

std.array.assocArray might also come in handy.