This is my first code in D, I feel like I'm already abusing mixin macros but I'm trying to avoid as much duplicate code/redundancies as possible. I would love a "static switch" as proposed in http://d.puremagic.com/issues/show_bug.cgi?id=6921 to replace the first AA, but since there isn't atm, a compile-time AA with a mixin is more elegant than seven "static if/else if" in single file.

enum TypeIndex : uint {
    Nil = 0,  // Undefined or dynamic value, depending on the context
    Number,
    String,
    Table,
    Classinst,
    Function,
    Bool   // Only used internally to avoid unnecessary bool->float conversions
}

// The rest below is for compile time only

private immutable string[TypeIndex] TyIdxtoDType = [
    TypeIndex.Nil : "DynamicValue",
    TypeIndex.Number : "Number",
    TypeIndex.String : "string",
    TypeIndex.Table : "TableHeader*",
    TypeIndex.Classinst : "ClassHeader*",
    TypeIndex.Function : "FunctionValue*",
    TypeIndex.Bool : "bool"
];

private template DType(TypeIndex tyIdx) {
    mixin("alias " ~ TyIdxtoDType(tyIdx) ~ " DType;");
}

But LDC gives me this error:
TalesRuntime.d(51): Error: expression '[cast(TypeIndex)0u:"DynamicValue", cast(TypeIndex)1u:"Number", cast(TypeIndex)2u:"string", cast(TypeIndex)3u:"TableHeader*", cast(TypeIndex)4u:"ClassHeader*", cast(TypeIndex)5u:"FunctionValue*", cast(TypeIndex)6u:"bool"]' is not a constant

And if I remove the immutable qualifier it says that the AA isn't available at compile time.
Probably related: http://d.puremagic.com/issues/show_bug.cgi?id=6238 , but yebblies says that associative arrays work fine in CTFE, so I don't understand what I'm doing wrong. Is there a better way to create an AA mapping an enum to D type names?

Turning it into an enum works.

I still have no idea why assigning an AA literal to an immutable AA isn't acceptable, but since it's only used at compile time it's probably better to make it an enum.

On Friday, 2 August 2013 at 21:57:14 UTC, Syniurge wrote:
> // The rest below is for compile time only
>
> private immutable string[TypeIndex] TyIdxtoDType = [
>     TypeIndex.Nil : "DynamicValue",
>     TypeIndex.Number : "Number",
>     TypeIndex.String : "string",
>     TypeIndex.Table : "TableHeader*",
>     TypeIndex.Classinst : "ClassHeader*",
>     TypeIndex.Function : "FunctionValue*",
>     TypeIndex.Bool : "bool"
> ];

Pretty sure you just need to start that with:

private enum TyIdxtoDType = [

On 08/03/2013 03:50 AM, Syniurge wrote:
> Turning it into an enum works.
>
> I still have no idea why assigning an AA literal to an immutable AA
> isn't acceptable,

It is a bug in the compiler implementation

> but since it's only used at compile time it's probably
> better to make it an enum.

Indeed.