dmd command line scripting experiments and observations

[Witold Baryluk]

On Monday, 25 December 2023 at 11:59:35 UTC, Witold Baryluk wrote:
...
>
> Inability to opt-in to allow implicit opCast casting are making 
> it not possible to develop fully dynamic and easy to use 
> solution.
>

Was thinking a bit after posting, and maybe there is some hope:


So, one of the possibly limited hacks would be to force `double` 
return type on `opBinary` when used with arithmetic operators

Instead of

```d
   auto opBinary(string op)(const ref DT other) const {
     if (numeric() && other.numeric()) {
       const n = number();
       const m = other.number();
       return DT(to!string(mixin("n " ~ op ~ " m")));
     }
     throw new Exception("cannot perform " ~ op ~ " on string");
   }
```

we do


```d
   double opBinary(string op)(const ref DT other) const if (op == 
"+" || op == "-" || op == "*" | op == "/" || op == "^^" || op == 
"|" || op == "&" || op == "^"){
     if (numeric() && other.numeric()) {
       const n = number();
       const m = other.number();
       return mixin("n " ~ op ~ " m");
     }
     throw new Exception("cannot perform " ~ op ~ " on string");
   }
   string opBinary(string op)(const ref DT other) const if (op == 
"~") {
     if (!numeric() && !other.numeric()) {
       return mixin("x_ " ~ op ~ " other.x_");
     }
     throw new Exception("cannot perform " ~ op ~ " on 
non-string");
   }
   ...
   // more overloads
   // ...
```

This is quite limit tho in general. What if I want to also 
support things more types than just double, and do it efficiently 
(cdouble, BigInt, other custom types).