▁be ▁extracted ▁into ▁a ▁new ▁procedure . ▁The ▁rule ▁was ▁popular ised ▁by ▁Martin ▁F ow ler ▁in ▁Ref actor ing ▁and ▁attributed ▁to ▁Don ▁Roberts . ▁ ▁Dup lication ▁is ▁considered ▁a ▁bad ▁practice ▁in ▁programming ▁because ▁it ▁makes ▁the ▁code ▁harder ▁to ▁maintain . ▁When ▁the ▁rule ▁encoded ▁in ▁a ▁rep licated ▁piece ▁of ▁code ▁changes , ▁who ever ▁maintain s ▁the ▁code ▁will ▁have ▁to ▁change ▁it ▁in ▁all ▁places ▁correctly . ▁ ▁However , ▁choosing ▁an ▁appropriate ▁design ▁to ▁avoid ▁dup lication ▁might ▁benefit ▁from ▁more ▁examples ▁to ▁see ▁patterns ▁in . ▁Att empt ing ▁prem ature ▁refactor ing ▁ris ks ▁selecting ▁a ▁wrong ▁abstra ction , ▁which ▁can ▁result ▁in ▁worse ▁code ▁as ▁new ▁requirements ▁emer ge ▁and ▁will ▁eventually ▁need ▁to ▁be ▁ref act ored ▁again . ▁ ▁The ▁rule ▁implies ▁that ▁the ▁cost ▁of ▁maintenance ▁certainly ▁out we igh s ▁the ▁cost ▁of ▁refactor ing ▁and ▁potential ▁bad ▁design ▁when ▁there ▁are ▁three ▁copies , ▁and ▁may ▁or ▁may ▁not ▁if ▁there ▁are ▁only ▁two ▁copies . ▁ ▁See ▁also ▁ ▁Copy - and - paste ▁programming ▁ ▁Don ' t ▁repeat ▁yourself ▁( DR Y ) ▁ ▁References ▁ ▁External ▁links ▁ ▁Category : Comput er ▁programming ▁fol kl ore <0x0A> </s> ▁Jenn ifer ▁Ann ▁" J en ny " ▁O ro pe za ▁( Se ptember ▁ 2 7 , ▁ 1 9 5 7 ▁– ▁October ▁ 2 0 , ▁ 2 0 1 0 ) ▁was ▁the ▁California ▁State ▁Senator ▁for ▁the