Convert a hex color string into r,g,b components.

[wobbles via Digitalmars-d-learn]

On Tuesday, 11 August 2015 at 22:11:51 UTC, Marcin Szymczak wrote:

> I would really love to solve this problem using ranges, because 
> i am learning how to use them. Unfortunately even such a simple 
> task seems so hard for me ;(

I think writing a simple function to parse a string into a Color 
would be best here.

Color parseRGBString(string theString){
         if(theString.length != 7)
                 throw new Exception("Error. Cannot parse to 
color: " ~ theString);
         return Color(
                 to!ubyte(theString[1..3], 16),
                 to!ubyte(theString[3..5], 16),
                 to!ubyte(theString[5..7], 16)
         );
}

I could probably do more to ensure that the string actually does 
represent a color (e.g. Check if no char is > F etc).

Also, using ranges isn't always required, theres no such thing as 
a "too simple" solution, as long as it works!

You can use this in a range then, e.g. say the user passes in 
lots of strings to your program, you can

listOfColors.map!(a => a.parseRGBString); // and now you have a 
lazily evaluated list of Color objects.