std.getopt: checking if an option has been passed

[Laeeth Isharc via Digitalmars-d-learn]

On Friday, 7 August 2015 at 11:40:54 UTC, Laeeth Isharc wrote:
> What's the best way to check if an (optional) argument has been 
> passed?  One way is to use a default value, but I wonder if 
> there is a tidier approach
>
> Thanks.
>
> (For startDate and endDate below)
>
> struct NanoClientOptions
> {
> 	string nanoUrl="tcp://127.0.0.1:9999";
> 	string[] tickers;
> 	DateTime startDate=DateTime(1,1,1);
> 	DateTime endDate=DateTime(9999,1,1);
> }
>
> auto helpInformation = getopt(
>     args,
>     "nanoUrl",  "Address of kaleidic data nanoserver eg 
> tcp://127.0.0.1:9999",	&options.nanoUrl,
> 	    std.getopt.config.required,	"ticker|t", 	"Tickers to 
> download data for",	&options.tickers,
> 	    "startDate|s", "Start Date",					&options.startDate,
> 	    "endDate|e", 	 "End Date",					&options.endDate
> 	    );
>
> Laeeth

I guess answer is simple: std.getopt doesn't handle DateTimes, so 
I have to use a callback, in which case I can just track whether 
it's been passed myself.