▁the ▁program . ▁ ▁Com bin ing ▁the ▁above ▁allows ▁generating ▁code ▁based ▁on ▁existing ▁declarations . ▁For ▁example , ▁D ▁serial ization ▁frameworks ▁can ▁enumerate ▁a ▁type ' s ▁members ▁and ▁generate ▁special ized ▁functions ▁for ▁each ▁serial ized ▁type ▁to ▁perform ▁serial ization ▁and ▁deser ial ization . ▁User - defined ▁attributes ▁could ▁further ▁indicate ▁serial ization ▁rules . ▁ ▁The ▁import ▁expression ▁and ▁compile - time ▁function ▁execution ▁also ▁allow ▁efficiently ▁implementing ▁domain - specific ▁languages . ▁For ▁example , ▁given ▁a ▁function ▁that ▁takes ▁a ▁string ▁containing ▁an ▁HTML ▁template ▁and ▁returns ▁equivalent ▁D ▁source ▁code , ▁it ▁is ▁possible ▁to ▁use ▁it ▁in ▁the ▁following ▁way : ▁ ▁// ▁Import ▁the ▁contents ▁of ▁example . htt ▁as ▁a ▁string ▁manifest ▁constant . ▁enum ▁html Template ▁= ▁import (" example . htt "); ▁ ▁// ▁Trans p ile ▁the ▁HTML ▁template ▁to ▁D ▁code . ▁enum ▁html D Code ▁= ▁html Template To D ( html Template ); ▁ ▁// ▁P aste ▁the ▁contents ▁of ▁html D Code ▁as ▁D ▁code . ▁mix in ( html D Code ); ▁ ▁Gener icity ▁in ▁E iff el ▁ ▁Gener ic ▁classes ▁have ▁been ▁a ▁part ▁of ▁E iff el ▁since ▁the ▁original ▁method ▁and ▁language ▁design . ▁The ▁foundation ▁publications ▁of ▁E iff el , ▁use ▁the ▁term ▁generic ity ▁to ▁describe ▁the ▁creation ▁and ▁use ▁of ▁generic ▁classes . ▁ ▁Basic / Un const rained ▁generic ity ▁Gener ic ▁classes ▁are ▁declared ▁with ▁their ▁class ▁name ▁and ▁a ▁list