Using lazily ?

[Ali Çehreli]

On 03/01/2012 02:25 PM, bioinfornatics wrote:
 > Le jeudi 01 mars 2012 à 23:10 +0100, Timon Gehr a écrit :
 >> S s;
 >> size_t tokenLength = "member1".length;
 >> void main(){
 >>       foreach(char[] line; stdin.byLine())
 >> foreach(m;__traits(allMembers,S)){
 >>           if(line[0..tokenLength] == m) mixin("s."~m) =
 >> line[tokenLength
 >> .. $].idup;
 >>       }
 >> }
 >
 > awesome :)
 >
 > can use hasMember instead allMembers ?

No, because both of those are compile-time features. Even if you used 
hasMember, the answer will always be true:

     if (__traits(hasMember, S, "member1"))

Yes, S has member1.

Note that Timon's inner foreach is a compile-time foreach, which is the 
equivalent of the following three lines:

if(line[0..tokenLength] == "member1") s.member1 = line[tokenLength .. 
$].idup;
if(line[0..tokenLength] == "member2") s.member2 = line[tokenLength .. 
$].idup;
if(line[0..tokenLength] == "member3") s.member3 = line[tokenLength .. 
$].idup;

There is no inner foreach looop that is executed at runtime.

Ali