Hi all,
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.
There is a c++ example in [this
link](https://jacobfilipp.com/DrDobbs/articles/CUJ/1998/9810/brill/brill.htm) which shows early binding to a known com server. But in that article, the author shows how to work with unknown servers using an IDL file.
So I collected the IDL file of MS Word and wrote a sample
interface in D like this -
```d
interface IWordApp : IDispatch
{
HRESULT getApplication(IDispatch** prop);
HRESULT getCreator(int* prop);
HRESULT getParent(IDispatch** prop);
....
HRESULT getUserName(BSTR* prop);
HRESULT setUserName2( BSTR prop);
}
```
Then tried to print the `Application.UserName` with this code.
```d
void getWordEarlyBinding() {
const IID iid = {0x00020970, 0x0000, 0x0000,
[0xC0, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x46]};
const GUID clsid = {0x000209FF, 0x0000, 0x0000,
[0xC0,0x00,0x00,0x00,0x00,0x00,0x00,0x46]};
IWordApp word;
auto hr1 = CoInitializeEx(null, COINIT_APARTMENTTHREADED );
auto cci_res = CoCreateInstance(&clsid, null,
CLSCTX_LOCAL_SERVER,
&iid, cast(void**)&word);
if (FAILED(cci_res)) {
writeln("CoCreateInstance failed for Word.Application");
}
scope(exit) word.Release();
BSTR bstrUserName = null;
auto hr = word.getUserName(&bstrUserName);
scope(exit) SysFreeString(bstrUserName);
if (SUCCEEDED(hr)) {
writefln("Word User Name BSTR: %s",
bstrUserName.to!string );
} else {
writeln("Failed to get UserName property.");
}
CoUninitialize();
}
```
And this code worked. It just printed my user name on console. Is
this approach safe ? Converting the IDL file entries to D
interface is a herculean task. The article I said earlier shows a
method to compile the IDL file with `midl.exe` and generate
header file & tlb file. But I couldn't create that. So, either
with the help of any AI tool, or a python script, I think we can
convert the IDL file to a proper D interface. Or is there any
better ways ? Let's discuss the possibilities of this.
Vinod Chandran.
