Using lazily ?

[bioinfornatics]

dear,
Noob question for know if D provide a shorter way i explain
we have a struct S:

struct S{
	string member1;
	string member2;
	string member3;
}

we parse a file:
File f = File("a path", "r");
S s;
sise_t tokenLength = "member1".length;
foreach( char[] line; f.byLine() )
    mixin("s." ~ line[0 .. tokenLength] ~ " = " ~ line[tokenLength ..
$]" ); // do not work because lien is not kno at compile time


I know this do not works i.e comment but it will save some line by
checking if is member1 2 or 3

They are a shorter way to do this use lazy ?