lazy variables

[aliak]

On Wednesday, 17 October 2018 at 20:32:40 UTC, Ali Çehreli wrote:
> On 10/17/2018 12:32 AM, aliak wrote:
>> [...]
>
> Not very clean but something like this:
>
> import std.stdio;
>
> struct LazyVar(alias exp) {
>     alias T = typeof(exp());
>     T value() {
>         static bool initialized = false;
>         static T val;
>
>         if (!initialized) {
>             val = exp();
>             initialized = true;
>         }
>         return val;
>     }
>
>     alias value this;
> }
>
> LazyVar!(() {
>     writeln("Doing heavy stuff");
>     return 42;
> }) a;
>
> void main() {
>     auto b = a.value;    // Must specify .value or
>     int c = a;           // must specify type of value (int).
>                          // Otherwise, b and c have type 
> LazyVar!(...)
>
>     // Some more usage
>     b = c = a;
>
>     assert(b == 42);
>     assert(c == 42);
> }
>
> Ali

Well I guess that's certainly a way to go about it :) Not very 
clean indeed though.