Experiments in early binding com object with D.

[Dennis]

On Monday, 3 November 2025 at 16:51:25 UTC, Vinod K Chandran 
wrote:
> I was worrying that there is no com support except the basic 
> building blocks like IUnknown and siblings. I know there is a 
> com library in Adam's arsd. But I couldn't successfully use 
> that. When I first tried Adam's library, I dreamed to write a 
> com client in D one day. When time permitted, I slowly 
> collected information about com and gradually made a confidence 
> to start with early binding. I want to make my library high 
> performance, so I choose early binding path.

I have succesfully made a D program connect to Excel using 
arsd.com last year. My strategy was to ask ChatGPT to give 
examples using Python win32com and then translate those calls to 
D by sometimes adding extra parenthesis (because of limitations 
of @property / opDispatch). The resulting code looks something 
like this:

```D
const choice = cell.Value().getD!string.ifThrown!Exception("");

// ...

auto c1 = sheet.Cells()(varsRow + i, varsValueColumn);
c1.Formula() = "=" ~ cs;
c1.Interior().Color() = color;
```

It's using the dynamic IDispatch interface instead of static 
bindings, which might be slower, but most calls take milliseconds 
to complete anyways and I highly doubt that all that time is 
spent on dynamic dispatch. The COM bridge and MS Office 
applications seem to be the limiting factor.

I recommend to start with dynamic calls and maybe create bindings 
from idl files later. If you explain what went wrong using 
arsd.com maybe I or someone else can help.