this is almost a workaround for the lack of named parameters

[timotheecour]

so i hacked up a working solution yesterday.
advantages over 
https://github.com/jacob-carlborg/mambo/blob/master/mambo/util/Reflection.d#L135:
no need to no arguments at CT (just names); allows optional and 
non optional ones; allows return value; also, mambo depends on 
tango and is hard to revive.

More later.


see:
https://github.com/timotheecour/dtools/blob/master/dtools/util/functional.d

nothing to install, just call:
rdmd --main -unittest dtools/util/functional.d


auto s=callNamed!(fun,`x,y`)(10,20);
given a function:
auto fun(int x,int y=2,double z=z_val, string z2="asdf");

Compile time errors will occur on duplicate param names, or ones 
that don't exist, or ones that are not optional and not provided 
(eg x, above)

Feel free to contribute / comment