D port of docopt

[Dicebot via Digitalmars-d-announce]

On Monday, 16 June 2014 at 21:21:47 UTC, Robert Schadek via 
Digitalmars-d-announce wrote:
> On 06/16/2014 11:11 PM, Dicebot via Digitalmars-d-announce 
> wrote:
>> On Monday, 16 June 2014 at 06:51:41 UTC, Jacob Carlborg wrote:
>>> Pretty cool idea. Are you aware of that in D you can, at 
>>> compile
>>> time, parse the doc string and generate a command line parser 
>>> for
>>> that particular documentation.
>>
>> I don't think it gives any advantage here :)
>>
>> docopt looks cool, though my I'd prefer something that works 
>> other way
>> around - automatically generates argument parsing code and help
>> messages from aggregate that represents configuration and/or 
>> CLI API
>> (with help of few UDA).
> +1 I could use reviews for this PR
> https://github.com/D-Programming-Language/phobos/pull/2072

Sure, will have a look.

Though I don't see how what I propose can fit into Phobos as 
std.getopt, it is something for an alternative module. The way I 
see it, getopt will be more suitable for small simple CLI 
implementations and that imaginary module - for programs with 
huge amount of options and complicated nested commands.

Something like this:

@help("
Header used to describe this configuration option block
")
struct CLI
{
     @descr("Some optional parameter")
     Optional!int param1;

     @descr("Mandatory parameter")
     int          param2;

     struct Command
     {
         string nested_param;

         void opCall(ref A outer)
         {
             // called after parsing relevant args into this 
instance
         }
     }

     Command command;
}

void main(string[] args)
{
     Config config;
     parseCLI!config(args);
     // ./app --param2 42 command --nested_param yay
}