Manipulating variables without evaluating them

[ag0aep6g]

On Monday, 8 May 2023 at 11:42:44 UTC, Dadoum wrote:
> ```d
> auto plistDict(alias AA)()
> {
> 	auto dict = new string[AA.length];
> 	foreach (key, value; AA)
> 	{
> 		dict[key] = value;
> 	}
> 	return dict;
> }
>
> import std.stdio;
>
> extern(C) void functionThatCannotBeEvaluatedAtCompileTime();
>
> string conversionFunction(string val) {
>     functionThatCannotBeEvaluatedAtCompileTime();
>     return val;
> }
>
> void main()
> {
> 	auto plist = plistDict!([
> 		0: "zero".conversionFunction, // Error: 
> `functionThatCannotBeEvaluatedAtCompileTime` cannot be 
> interpreted at compile time, because it has no available source 
> code
> 		1: "one".conversionFunction,
> 		2: "two".conversionFunction,
> 	]);
> 	plist.writeln;
> }
> ```
[...]
> Is there a way to use the associative array here at compile 
> time while avoiding the evaluation of those keys?

Instead of passing values, pass functions that return the values:

```d
	auto plist = plistDict!([
		0: () => "zero".conversionFunction,
		1: () => "one".conversionFunction,
		2: () => "two".conversionFunction,
	]);
```

And in `plistDict`, call the functions:

```d
	static foreach (key, fun; AA)
	{
		dict[key] = fun();
	}
```