When programming i have encountered a simple ( i think ) problem,
yet i can't get my head around it. I am trying to convert a
string ( like "#FF00FF" for magenta ) into a color. I figured out
that i need to skip the first character '#' and then using
"chunks" range convert each pair of 2 chars into a number and
assign it to specific component. The snippet looks like this
Color color;
auto chunk = chunks( str[1..$], 2 );
color.r = to!ubyte( chunk.front, 16 ); chunk.popFront;
color.g = to!ubyte( chunk.front, 16 ); chunk.popFront;
color.b = to!ubyte( chunk.front, 16 ); chunk.popFront;
But the compilation fails, stating
/usr/include/dlang/dmd/std/conv.d(295): Error: template
std.conv.toImpl cannot deduce function from argument types
!(ubyte)(Take!string, int), candidates are:
/usr/include/dlang/dmd/std/conv.d(361): std.conv.toImpl(T,
S)(S value) if (isImplicitlyConvertible!(S, T) &&
!isEnumStrToStr!(S, T) && !isNullToStr!(S, T))
/usr/include/dlang/dmd/std/conv.d(475): std.conv.toImpl(T,
S)(ref S s) if (isRawStaticArray!S)
/usr/include/dlang/dmd/std/conv.d(491): std.conv.toImpl(T,
S)(S value) if (!isImplicitlyConvertible!(S, T) &&
is(typeof(S.init.opCast!T()) : T) && !isExactSomeString!T &&
!is(typeof(T(value))))
/usr/include/dlang/dmd/std/conv.d(542): std.conv.toImpl(T,
S)(S value) if (!isImplicitlyConvertible!(S, T) && is(T ==
struct) && is(typeof(T(value))))
/usr/include/dlang/dmd/std/conv.d(591): std.conv.toImpl(T,
S)(S value) if (!isImplicitlyConvertible!(S, T) && is(T == class)
&& is(typeof(new T(value))))
/usr/include/dlang/dmd/std/conv.d(295): ... (9 more, -v to
show) ...
source/engine/graphics/core.d(43): Error: template instance
std.conv.to!ubyte.to!(Take!string, int) error instantiating
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 ;(
