Acme: A User Interface for Programmers

Rob Pike [email protected]−labs.com

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______OHECEn=llO =FFA=HA@ En Proc. of the Winter 1994 USENIX Conf., FF. !- !", 5=n .H=n?EI?o, +) ­ ­

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Nuances and heuristics )KIAHEnJAHB=?AIDoKl@noJ onlO FHoLE@A JDA nA?AII=HO BKn?JEonI, EJ IDoKl@ =lIo feel HECDJ. 1n B=?J, EJ IDoKl@ =lmoIJ noJ >A BAlJ =J =ll; MDAn onA noJE?AI = KIAH EnJAHB=?A, onA EI @EIJH=?JA@ BHom JDA jo> =J D=n@ [2EkA&&]. 6o =FFHo=?D JDEI EnLEIE>ElEJO, IomA oB )?mAߣI FHoFAHJEAI =n@ BA=JKHAI =HA JDAHA jKIJ Jo m=kA JDA oJDAHI A=IO Jo KIA. M=nO =HA >=IA@on=BKn@=mAnJ=lFHEn?EFlAoBCoo@@AIECn:lAJJDAm=?DEnA@oJDAMoHk. )?mA JHEAI Jo =LoE@ nAA@lAII ?lE?kEnC =n@ JOFEnC. 6DAHA EI no ߢ?lE?k-Jo-JOFAߣ, AlEmE­ n=JEnC = >KJJon ?lE?k. 6DAHA =HA no FoF-KF oH FKll-@oMn mAnKI, AlEmEn=JEnC JDA moKIA =?JEon nAA@A@ Jo m=kA = mAnK =FFA=H. 6DA oLAH=ll @AIECn EI EnJAn@A@ Jo m=kA JANJ on JDA I?HAAn KIABKl MEJDoKJ ?oFOEnC oH HAJOFEnC; JDA M=OI En MDE?D JDEI D=FFAnI EnLolLA JDA?om>En=JEonoBm=nO=IFA?JIoBJDAEnJAHB=?A. )?mA JElAI EJI MEn@oMI =n@ Fl=?AI JDAm =KJom=JE?=llO Jo =LoE@ =IkEnC JDA KIAH Jo Fl=?A =n@ =HH=nCA JDAm. .oH JDEI FolE?O Jo IK??AA@, JDA =KJom=JE? Fl=?AmAnJ mKIJ >AD=LA MAll AnoKCD JD=J JDA KIAH EI KIK=llO ?onJAnJ MEJD JDA lo?=JEon oB = nAM MEn@oM. 6DA IOIJAm MEll nALAH CAJ EJ HECDJ =ll JDA JEmA, >KJ En FH=?JE?A moIJ MEn@oMI =HA KIA@ =J lA=IJ BoH = MDElA MDAHA )?mA BEHIJ Fl=?AI JDAm. 6DAHA D=LA >AAn IALAH=l ?omFlAJA HAMHEJAI oB JDA DAKHEIJE?I BoH Fl=?EnC = nAM MEn@oM, =n@ MEJD A=?D HAMHEJA JDA IOIJAm >A?=mA noJE?A=>lO moHA ?omBoHJ=>lA. 6DA HKlAI =HA =I BolloMI, =lJDoKCD JDAO =HA IJEll IK>jA?J Jo EmFHoLAmAnJ. 6DA MEn@oM =FFA=HI En JDA ߢ=?JELAߣ ?olKmn, JD=J moIJ HA?AnJlO KIA@ BoH JOFEnC oH IAlA?JEnC. -NA?KJEnC =n@ IA=H?DEnC @o noJ =BBA?J JDA ?DoE?A oB =?JELA ?olKmn, Io MEn@oMI oB ?omm=n@I =n@ IK?D @o noJ @H=M nAM MEn@oMI JoM=H@I JDAm, >KJ H=JDAH lAJ JDAm BoHm nA=H JDA J=HCAJI oB JDAEH =?JEonI. OKJFKJ AHHoH MEn@oMI =lM=OI =FFA=H JoM=H@I JDA HECDJ, =M=O BHom A@EJA@ JANJ, MDE?D EI JOFE?=llO kAFJ JoM=H@I JDAlABJ. 9EJDEnJDA?olKmn,IALAH=l?omFAJEnC@AIEHAI=HA>=l=n?A@Jo@A?E@AMDAHA =n@ DoM l=HCA JDA MEn@oM IDoKl@ >A: l=HCA >l=nk IF=?AI IDoKl@ >A ?onIKmA@; ANEIJEnC JANJ IDoKl@ HAm=En LEIE>lA; ANEIJEnC l=HCA MEn@oMI IDoKl@ >A @ELE@A@ >ABoHA Im=ll onAI; =n@ JDAMEn@oMIDoKl@=FFA=HnA=HJDAonA?onJ=EnEnCJDA=?JEonJD=J?=KIA@EJI?HA=JEon. )?mA >En@I IomA =?JEonI Jo ?DoH@I oB moKIA >KJJonI. 6DAIA En?lK@A Cut =n@ Paste Io JDAIA ?ommon oFAH=JEonI ?=n >A @onA MEJDoKJ moLEnC JDA moKIA. )noJDAH EI = M=O Jo =FFlO = ?omm=n@ En onA MEn@oM Jo JANJ oBJAn = BElA n=mA En =noJDAH, =LoE@­ EnCJDA=?JEonInAA@A@Jo=IIAm>lAJDA?omm=n@JANJK=llO. ­$­

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)I =n ANJH= BA=JKHA, )?mA HA?oCnEzAI BElA n=mAI En =nClA >H=?kAJI <> =I n=mAI oB BElAI En IJ=n@=H@ @EHA?JoHEAI oB En?lK@A BElAI, m=kEnC EJ FoIIE>lA BoH EnIJ=n?A Jo look =J MEJD=IEnClA?lE?k. 0AHAߣI =n AN=mFlA Jo @AmonIJH=JA DoM JDA =?JEonI =n@ @AB=KlJI MoHk JoCAJDAH. )IIKmA /sys/src/cmd/sam/regexp.c EI oFAn =n@ D=I >AAn A@EJA@. 9A MHEJA EJ ANA?KJA Put En JDA J=C; on?A JDA BElA EI MHEJJAn, )?mA HAmoLAI JDA MoH@ BHom JDA J=C =n@ JOFA mk En JDA J=C. 9A ANA?KJA mk =n@CAJIomAAHHoHI,MDE?D=FFA=HEn=nAMMEn­ @oM l=>AlA@ /sys/src/cmd/sam/+Errors. 6DA ?KHIoH moLAI =KJom=JE?=llO Jo JD=JMEn@oM. 5=OJDAAHHoHEI

main.c:112: incompatible types on assignment to ‘pattern’

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Coupling to existing programs )?mAߣI IOnJ=N BoH BElA n=mAI =n@ =@@HAIIAI m=kAI EJ A=IO BoH oJDAH FHoCH=mI Jo ?onnA?J=KJom=JE?=llOJo)?mAߣI?=F=>ElEJEAI. .oHAN=mFlA,JDAoKJFKJoB

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#pragma src "/sys/src/libregexp" Jo DA=@AH BElAI; ?oKFlA@ MEJD )?mAߣI =>ElEJO Jo lo?=JA = DA=@AH BElA, JDEI FHoLE@AI = B=IJ, kAO>o=H@lAIIM=OJoCAJJDAIoKH?A=IIo?E=JA@MEJD=lE>H=HO. .En=llO, )?mA @EHA?JI JDA IJ=n@=H@ oKJFKJ oB FHoCH=mI EJ HKnI Jo MEn@oMI l=>AlA@ >O JDA @EHA?JoHO En MDE?D JDA FHoCH=m EI HKn. )?mAߣI IFlEJJEnC oB JDA oKJFKJ EnJo @EHA?JoHO-l=>AlA@ MEn@oMI EI = Im=ll BA=JKHA JD=J D=I = m=joH ABBA?J: lo?=l BElA n=mAI FHEnJA@ >O FHoCH=mI ?=n >A EnJAHFHAJA@ @EHA?JlO >O )?mA. *O En@EHA?JlO ?oKFlEnCJDAoKJ­ FKJ oB FHoCH=mI Jo JDA EnFKJ, EJ =lIo IEmFlEBEAI JDA m=n=CAmAnJ oB IoBJM=HA JD=J o??K­ FEAImKlJEFlA@EHA?JoHEAI.

Coupling to new programs LEkA m=nO 2l=n ' FHoCH=mI, )?mA oBBAHI = FHoCH=mm=>lA EnJAHB=?A Jo oJDAH FHo­ CH=mI >O =?JEnC =I = BElA IAHLAH. 6DA >AIJ AN=mFlA oB IK?D = BElA IAHLAH EI JDA MEn@oM IOIJAm 8½ [2EkA' ], MDE?D ANFoHJI BElAI MEJD n=mAI IK?D =I screen, cons, =n@ mouse JDHoKCD MDE?D =FFlE?=JEonI m=O =??AII JDA 1/O ?=F=>ElEJEAI oB JDA MEn@oMI. 8½ FHoLE@AI = distinct IAJ oB BElAI BoH A=?D MEn@oM =n@ >KEl@I = FHEL=JA BElA n=mA IF=?A BoH JDA ?lEAnJI HKnnEnC ߢEnߣ A=?D MEn@oM; ?lEAnJI En IAF=H=JA MEn@oMI IAA @EIJEn?J BElAI MEJD JDA I=mA n=mAI BoH AN=mFlA /dev/mouse. )?mA, lEkA JDA FHo?AII BElA IOIJAm [22669'!], EnIJA=@ =IIo?E=JAI A=?D MEn@oM MEJD = @EHA?JoHO oB BElAI; JDA BElAI oB A=?D MEn@oM =HA LEIE>lA Jo =nO =FFlE?=JEon. 6DEI @EBBAHAn?A HABlA?JI = @EBBAHAn?A En DoM JDA IOIJAmI =HA KIA@: 8½ JAllI = ?lEAnJ MD=J kAO>o=H@ =n@ moKIA =?JELEJO D=I D=FFAnA@ En EJI MEn@oM; )?mA JAllI = ?lEAnJ MD=J ?D=nCAI JD=J =?JELEJO MHoKCDJ on =nO MEn@oM EJ =IkI =>oKJ. 2KJJEnC EJ =noJDAH M=O, 8½ An=>lAI JDA ?onIJHK?JEon oB EnJAH=?JELA =FFlE?=JEonI; )?mAFHoLE@AIJDAEnJAH=?JEonBoH=FFlE?=JEonI. 6DA HooJ oB )?mAߣI BElA IOIJAm EI moKnJA@ KIEnC 2l=n ' oFAH=JEonI on JDA @EHA?JoHO /mnt/acme. 1n JD=J HooJ @EHA?JoHO =FFA=HI = @EHA?JoHO BoH A=?D MEn@oM, nKm>AHA@ MEJD JDA MEn@oMߣI E@AnJEBEAH, =n=loCoKI Jo = FHo?AII E@AnJEBEAH, BoH AN=mFlA /mnt/acme/27. 6DA MEn@oMߣI @EHA?JoHO ?onJ=EnI $ BElAI: /mnt/acme/27/addr, body, ctl, data, event, =n@ tag. 6DA body =n@ tag BElAI ?onJ=En JDA JANJ oB JDA HAIFA?JELA F=HJI oB JDA MEn@oM; JDAO m=O >A HA=@ Jo HA?oLAH JDA ?onJAnJI. ,=J= MHEJJAn Jo JDAIA BElAI EI =FFAn@A@ Jo JDA JANJ; seeks =HA ECnoHA@. 6DA addr =n@ data BElAI ­&­

FHoLE@A H=n@om =??AII Jo JDA ?onJAnJI oB JDA >o@O. 6DA addr BElA EI MHEJJAn Jo IAJ = ?D=H=?JAH FoIEJEon MEJDEn JDA >o@O; JDA data BElA m=O JDAn >A HA=@ Jo HA?oLAH JDA ?on­ JAnJI =J JD=J FoIEJEon, oH MHEJJAn Jo ?D=nCA JDAm. 6DA J=C EI =IIKmA@ Im=ll =n@ IFA?E=l-FKHFoIA AnoKCD noJ Jo nAA@ IFA?E=l JHA=JmAnJ. )lIo, addr En@ANAI >O ?D=H=?­ JAH FoIEJEon, MDE?D EI noJ JDA I=mA =I >OJA oBBIAJ En 2l=n 'ߣI mKlJE->OJA ?D=H=?JAH IAJ [2EkA'!]. 6DA BoHm=J =??AFJA@ >O JDA addr BElA EI AN=?JlO JDA IOnJ=N oB =@@HAIIAI MEJDEn JDA KIAH EnJAHB=?A, FAHmEJJEnC HACKl=H ANFHAIIEonI, lEnA nKm>AHI, =n@ ?omFoKn@ =@@HAIIAI Jo >A IFA?EBEA@. .oH AN=mFlA, Jo HAFl=?A JDA ?onJAnJI oB lEnAI ! JDHoKCD %, MHEJAJDAJANJ

3,7

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name /adm/users

IAJI JDA n=mA En JDA J=C oB JDA MEn@oM Jo /adm/users. OJDAH ?omm=n@I =lloM @AlAJ­ EnC JDA MEn@oM, MHEJEnC EJ Jo = BElA, =n@ Io on. 4A=@EnC JDA ctl BElA HA?oLAHI = BENA@- BoHm=J IJHEnC ?onJ=EnEnC # JANJK=l nKm>AHIߞJDA MEn@oM E@AnJEBEAH, JDA nKm>AH oB ?D=H­ =?JAHI En JDA J=C, JDA nKm>AH En JDA >o@O, =n@ IomA IJ=JKI EnBoHm=JEonߞBolloMA@ >O JDA JANJoBJDAJ=C,KFJo=nAMlEnA. 6DA l=IJ BElA, event, EI JDA moIJ KnKIK=l. ) FHoCH=m HA=@EnC = MEn@oMߣI event BElA EI noJEBEA@ oB =ll ?D=nCAI Jo JDA JANJ oB JDA MEn@oM, =n@ EI =IkA@ Jo EnJAHFHAJ =ll mE@@lA- =n@ HECDJ->KJJon =?JEonI. 6DA @=J= F=IIA@ Jo JDA FHoCH=m EI BENA@-BoHm=J =n@ HAFoHJI JDA IoKH?A oB JDA =?JEon kAO>o=H@, moKIA, ANJAHn=l FHoCH=m, AJ?., EJI lo?=JEon MD=J M=I FoEnJA@ =J oH mo@EBEA@, =n@ EJI n=JKHA ?D=nCA, IA=H?D, ANA?KJEon, AJ?.. 6DEI mAII=CA,BoHAN=mFlA,

MI15 19 0 4 time

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@ALE?AI [2HAI'!]. 6DA =?J oB oFAnEnC =nO BElA En new ?HA=JAI = nAM )?mA MEn@oM; JDKI JDAIDAll?omm=n@

grep −n var *.c > /mnt/acme/new/body Fl=?AI EJI oKJFKJ En JDA >o@O oB = BHAID MEn@oM. MoHA IoFDEIJE?=JA@ =FFlE?=JEonI m=O oFAn new/ctl, HA=@ EJ Jo @EI?oLAH JDA nAM MEn@oMߣI E@AnJEBEAH, =n@ JDAn oFAn JDA MEn@oMߣIoJDAHBElAIEnJDAnKm>AHA@@EHA?JoHO.

Acme−specific programs )lJDoKCD)?mAEIEnF=HJ=n=JJAmFJJomoLA>AOon@JOFAI?HEFJI,JDAOMEll FHo>=>lO =lM=OI D=LA KJElEJO. 6DA BEHIJ FHoCH=m MHEJJAn BoH )?mA M=I JDAHABoHA onA Jo HKn = IDAll oH oJDAH JH=@EJEon=l EnJAH=?JELA =FFlE?=JEon En = MEn@oM, JDA )?mA =n=loC oB xterm. 6DEI FHoCH=m, win, D=I = IEmFlA IJHK?JKHA: EJ =?JI =I = JMo-M=O EnJAHmA@E=HO >AJMAAn )?mA =n@ JDA IDAll, ?HoII-?onnA?JEnC JDA IJ=n@=H@ EnFKJ =n@ oKJFKJ oB JDA IDAll Jo JDA JANJ oB JDA MEn@oM. 6DA IJOlA oB EnJAH=?JEon EI mo@AlA@ =BJAH mux [2EkA&&]: IJ=n@=H@ oKJFKJ EI =@@A@ Jo JDA MEn@oM =J JDA output point; JANJ JOFA@ =BJAH JDA oKJFKJ FoEnJ EI m=@A =L=El=>lA on IJ=n@=H@ EnFKJ MDAn = nAMlEnA EI JOFA@. )BJAH AEJDAH oB JDAIA =?JEonI, JDA oKJFKJ FoEnJ EI =@L=n?A@. 6DEI EI @EBBAHAnJ BHom JDA MoHkEnC oB = HACKl=H JAHmEn=l, FAHmEJJEnC ?KJ-=n@-F=IJA A@EJEnC oB =n EnFKJ lEnA KnJEl JDA nAMlEnA EI JOFA@. )H>EJH=HO A@EJEnC m=O >A @onA Jo =nO JANJ En JDA MEn@oM. 6DA EmFlAmAnJ=JEon oB win, KIEnC JDA event, addr, =n@ data BElAI, EI IJH=ECDJBoHM=H@. Win nAA@I no ?o@A BoH D=n@lEnC JDA kAO>o=H@ =n@ moKIA; EJ jKIJ monEJoHI JDA ?onJAnJI oB JDA MEn@oM. NonAJDAlAII, EJ =lloMI )?mAߣI BKll A@EJEnC Jo >A =FFlEA@ Jo IDAll ?omm=n@I. 6DA @ELEIEon oB l=>oH >AJMAAn win =n@ Acme ?onJH=IJA@ MEJD xterm =n@ JDA : IAHLAH @AmonIJH=JAI DoM mK?D MoHk )?mA D=n@lAI =KJom=JE?=llO. Win EI EmFlAmAnJA@ >O = IEnClA IoKH?A BElA #$lEnAIlonC=n@D=InoCH=FDE?I?o@A. Win KIAI JDA mE@@lA =n@ HECDJ >KJJonI Jo ?onnA?J EJIAlB En = ?onIEIJAnJ M=O MEJD JDA HAIJ oB )?mA. 6DA mE@@lA >KJJon IJEll ANA?KJAI ?omm=n@I, >KJ En = IJOlA moHA IKEJA@ Jo JOFAI?HEFJI. 6ANJ IAlA?JA@ MEJD JDA mE@@lA >KJJon EI JHA=JA@ =I EB EJ D=@ >AAn JOFA@ =BJAH JDA oKJFKJ FoEnJ, mK?D =I = IEmEl=H BA=JKHA En xterm oH 8½, =n@ JDAHABoHA ?=KIAI EJ Jo >A ߢANA?KJA@ߣ >O JDA =FFlE?=JEon HKnnEnC En JDA MEn@oM. 4ECDJ >KJJon =?JEonI =HA HABlA?JA@ >=?k Jo )?mA >KJ HABAH Jo JDA =FFHoFHE=JA BElAI >A?=KIA win Fl=?AI JDAn=mAoBJDA?KHHAnJ@EHA?JoHOEnJDAJ=CoBJDAMEn@oM. 1BJDAIDAllEIHKnnEnC, = IEm­ FlA IDAll BKn?JEon HAFl=?EnC JDA cd ?omm=n@ ?=n m=EnJ=En JDA J=C =I JDA IDAll n=LEC=JAI JDABElAIOIJAm. 6DEImA=nI,BoHAN=mFlA,JD=J=HECDJ>KJJon?lE?kon = BElA mAnJEonA@ En =n ls lEIJEnCoFAnIJDABElAMEJDEn)?mA. )noJDAH )?mA-IFA?EBE? FHoCH=m EI = m=El HA=@AH JD=J >ACEnI >O FHAIAnJEnC, En = MEn@oM, = lEIJEnC oB JDA mAII=CAI En JDA KIAHߣI m=El>oN, onA FAH lEnA. 0AHA JDA mE@@lA =n@ HECDJ >KJJon =?JEonI =HA mo@EBEA@ Jo HABAH Jo m=El ?omm=n@I =n@ mAII=CAI, >KJ JDA ?D=nCA BAAlI n=JKH=l. +lE?kEnC JDA HECDJ >KJJon on = lEnA ?HA=JAI = nAM MEn@oM =n@ @EI­ Fl=OI JDA mAII=CA JDAHA, oH, EB EJߣI =lHA=@O @EIFl=OA@, moLAI JDA moKIA Jo JD=J MEn@oM. 6DA mAJ=FDoH EI JD=J JDA m=El>oN EI = @EHA?JoHO MDoIA ?onIJEJKAnJ BElAI =HA mAII=CAI. 6DA m=El FHoCH=m =lIo Fl=?AI IomA HAlAL=nJ ?omm=n@I En JDA J=C lEnAI oB JDA MEn@oMI; BoH AN=mFlA, ANA?KJEnC JDA MoH@ Reply En = mAII=CAߣI J=C ?HA=JAI = nAM MEn@oM En MDE?D Jo ?omFoIA = mAII=CA Jo JDA IAn@AH oB JDA oHECEn=l; Post JDAn @EIF=J?DAI EJ. 1n IK?D MEn@oMI, JDA =@@HAIIAA EI jKIJ = lEIJ oB n=mAI on JDA BEHIJ lEnA oB JDA >o@O, MDE?D m=O >A A@EJA@ Jo =@@ oH ?D=nCA HA?EFEAnJI. 6DA FHoCH=m =lIo monEJoHI JDA m=El>oN, KF@=JEnCJDAߢ@EHA?JoHOߣ =InAMmAII=CAI=HHELA. 6DA m=El FHoCH=m EI =I IEmFlA =I EJ IoKn@I; =ll JDA MoHk oB EnJAH=?JEon, A@EJEnC, =n@ m=n=CAmAnJ oB JDA @EIFl=O EI @onA >O )?mA. 6DA onlO @EBBE?KlJ IA?JEonI oB JDA  lEnAI oB ?o@A ?on?AHn DonoHEnC JDA ANJAHn=l FHoJo?olI BoH m=n=CEnC JDA m=El>oN =n@ ?onnA?JEnCJo sendmail. ­ ­

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0,$ x/regexp/ c/replacement/ En)?mAߣIA@EJoH>A?omAI

e ’file:0,$’ | x ’/regexp/’ | c ’replacement’ 6o KIA JDA )?mA A@EJEnC ?omm=n@I, oFAn /acme/edit/guide, KIA JDA moKIA =n@ kAO>o=H@ Jo A@EJ onA oB JDA ?omm=n@I Jo JDA HECDJ BoHm, =n@ ANA?KJA EJ MEJD JDA mE@@lA >KJJon. )?mAߣI ?onJANJ HKlAI BEn@ JDA =FFHoFHE=JA >En=HEAI En /acme/edit H=JDAH JD=n /bin; JDA ABBA?J EI Jo JKHn /acme/edit EnJo = Jool>oN ?onJ=EnEnC JoolI =n@ EnIJHK?JEonI JDA CKE@A BElA BoH JDAEH KIA. 1n B=?J, JDA IoKH?A BoH JDAIA JoolI EI =lIo JDAHA, En JDA @EHA?JoHO /acme/edit/src. 6DEI IAJKF =lloMI IomA ?onJHol oB JDA BElA n=mAIF=?A BoH >En=HO FHoCH=mI; noJ onlO @oAI EJ CHoKF HAl=JA@ FHoCH=mI, EJ FAHmEJI JDA KIA oB ?ommon n=mAI BoH Kn?ommon jo>I. .oH AN=mFlA, JDA IEnClA-lAJJAHn=mAIMoKl@ >A KnMEIA En = @EHA?JoHO En ALAHOonAߣI IA=H?D F=JD; DAHA JDAO =HA onlO LEIE>lA MDAn HKn­ nEnCA@EJEnC?omm=n@I. 1n O>AHon, IK?D = ?ollA?JEon MoKl@ >A ?=llA@ = tool =n@ MoKl@ ?onIEIJ oB = IAJ oB AnJHO FoEnJI En = mo@KlA =n@ = mAnK-lEkA FEA?A oB JANJ ?onJ=EnEnC HAFHAIAnJ=JELA ?om­ m=n@I JD=J m=O >A A@EJA@ Jo IKEJ =n@ ANA?KJA@. 6DAHA EI, En B=?J, = Jool ?=llA@ Edit En O>AHon. 6o FHoLE@A HAl=JA@ BKn?JEon=lEJO, )?mA ANFloEJI JDA @EHA?JoHO =n@ BElA IJHK?JKHA oBJDAKn@AHlOEnC IOIJAm, H=JDAH JD=n JDA mo@KlA IJHK?JKHA oB JDA l=nCK=CA; JDEI BEJI MAll MEJD 2l=n 'ߣI BElA-oHEAnJA@ FDEloIoFDO. 5K?D JoolI =HA ?AnJH=l Jo JDA MoHkEnC oB O>AHon >KJ JDAO =HA lAII KIA@ En )?mA, =J lA=IJ Io B=H. 6DA m=En HA=Ion EI FHo>=>lO JD=J )?mAߣI FHoCH=m EnJAHB=?A FAHmEJI =n ANJAHn=l FHoCH=m Jo HAm=En ANA?KJEnC En JDA >=?kCHoKn@, FHoLE@EnC EJI oMn ?omm=n@I =I nAA@A@ BoH AN=mFlA, JDA Reply ?omm=n@ En JDA m=El FHoCH=m;O>AHonKIAIJoolIJoEmFlAmAnJIK?DIAHLE?AI>A?=KIAEJImKIJEnLokA=BHAID FHoCH=m BoH A=?D ?omm=n@. )lIo, )?mAߣI >AJJAH EnJACH=JEon =lloMI moHA >=IE? BKn?­ JEonI Jo >A D=n@lA@ EnJAHn=llO; JDA HECDJ moKIA >KJJon ?oLAHI = loJ oB JDA >=IE? KJElEJO oB JDA A@EJEnC JoolI En O>AHon. NonAJDAlAII, =I moHA =FFlE?=JEonI =HA MHEJJAn BoH )?mA, m=nO=HAIKHAJoJ=kAJDEIO>AHonJool-lEkABoHm.

Comparison with other systems )?mAߣI EmmA@E=JA =n?AIJoH EI 0AlF [2EkA' ], =n ANFAHEmAnJ=l IOIJAm MHEJJAn = BAM OA=HI =Co =I = BEHIJ JHO =J ANFloHEnC IomA oB O>AHonߣI E@A=I En =n ANEIJEnC oFAH=JEnC IOI­ JAm. *AIE@AI mK?D >AJJAH AnCEnAAHEnC, )?mAߣI =@L=n?AI oLAH 0AlF En?lK@A JDA =?JEonI oB JDA HECDJ >KJJon 0AlF D=@ noJDEnC ?omF=H=>lA, JDA =>ElEJO Jo ?onnA?J lonC-HKnnEnC ­ ­

FHoCH=mI Jo JDA KIAH EnJAHB=?A 0AlF D=@ no =n=loC oB JDA event BElA, =n@ JDA Im=ll >KJ EmFoHJ=nJ ?D=nCA Jo IFlEJ ?omm=n@ oKJFKJ EnJo MEn@oMI l=>AlA@ MEJD JDA @EHA?JoHO EnMDE?DJDA?omm=n@IHKn. MoIJ oB )?mAߣI IJOlA, DoMALAH, @AHELAI BHom JDA KIAH EnJAHB=?A =n@ MEn@oM IOIJAm oB O>AHon [9EHJ&', 4AEI' ]. O>AHon En?lK@AI = FHoCH=mmEnC l=nCK=CA =n@ oFAH=JEnC IOIJAm, MDE?D )?mA EnIJA=@ >oHHoMI BHom =n ANEIJEnC IOIJAm, 2l=n '. 9DAn 1 BEHIJ I=M O>AHon, En '&&, 1 M=I IJHK?k >O JDA IEmFlE?EJO oB EJI KIAH EnJAHB=?A, F=HJE?Kl=HlO EJI l=?k oB mAnKI =n@ EJI AlAC=nJ KIA oB mKlJEFlA moKIA >KJJonI. 6DA IOIJAm IAAmA@ HAIJHE?­ JELA, JDoKCDߞIEnClA FHo?AII, IEnClA l=nCK=CA, no nAJMoHkEnC, ALAnJ-@HELAn FHoCH=mmEnCߞ=n@ B=ElA@ Jo BolloM JDHoKCD on IomA oB EJI oMn E@A=I. .oH AN=mFlA, JDA mE@@lA moKIA >KJJon D=@ Jo >A FoEnJA@ =??KH=JAlO =n@ JDA HECDJ >KJJon M=I AIIAnJE=llO KnKIA@. )?mA @oAI BolloM JDHoKCD: Jo JDA >=IE? E@A= Fl=nJA@ >O O>AHon, EJ =@@I JDA =>ElEJO Jo HKn on @EBBAHAnJ oFAH=JEnC IOIJAmI =n@ D=H@M=HA, ?onnA?JEon Jo ANEIJEnC =FFlE­ ?=JEonI En?lK@EnC EnJAH=?JELA onAI IK?D =I IDAllI =n@ @A>KCCAHI, IKFFoHJ BoH mKlJEFlA FHo?AIIAI, JDA HECDJ moKIA >KJJonߣI BA=JKHAI, JDA @AB=KlJ =?JEonI =n@ ?onJANJ- @AFAn@AnJ FHoFAHJEAI oB ANA?KJEon =n@ IA=H?DEnC, =n@ = DoIJ oB lEJJlA JoK?DAI IK?D =I moLEnC JDA moKIA ?KHIoH JD=J m=kA JDA IOIJAm moHA FlA=I=nJ. )J JDA momAnJ, JDoKCD, O>AHon @oAI D=LA onA @EIJEn?J =@L=nJ=CA: EJ En?oHFoH=JAI CH=FDE?=l FHoCH=mI MAll EnJo EJImo@Al,=nEIIKA)?mAD=InoJOAJB=?A@. )?mA ID=HAI MEJD JDA M=?EnJoID = @AIEHA Jo KIA JDA moKIA MAll =n@ EJ EI MoHJD ?omF=HEnC JDA HAIKlJI. 6DA moKIA on JDA M=?EnJoID D=I = IEnClA >KJJon, Io mAnKI =HA AIIAnJE=l=n@JDAmoKIAmKIJBHAGKAnJlOmoLA = lonC M=O Jo HA=?D JDA =FFHoFHE=JA BKn?­ JEon. )n En@E?=JEon JD=J JDEI IJOlA D=I JHoK>lA EI JD=J =FFlE?=JEonI FHoLE@A kAO>o=H@ IAGKAn?AI Jo EnLokA mAnK IAlA?JEonI =n@ KIAHI oBJAn FHABAH JDAm. ) @AAFAH ?omF=HE­ Ion EI JD=J JDA M=?EnJoID KIAI FE?JKHAI MDAHA )?mA KIAI JANJ. 1n ?onJH=IJ Jo FE?JKHAI, JANJ ?=n >A A@EJA@ GKE?klO, ?HA=JA@ on @Am=n@, =n@ BEnA-JKnA@ Jo JDA jo> =J D=n@; ?on­ IE@AH =@@EnC =n oFJEon Jo = ?omm=n@. 1J EI =lIo IAlB-HABAHAnJE=l; )?mA @oAInߣJ nAA@ mAnKI >A?=KIA =nO JANJ ?=n >A En ABBA?J = mAnK EJAm. 6DA HAIKlJ EI JD=J, =lJDoKCD = M=?EnJoID I?HAAn EI ?AHJ=EnlO FHAJJEAH =n@ FHo>=>lO moHA =JJH=?JELA, AIFA?E=llO Jo >ACEn­ nAHI, =n )?mA I?HAAn EI moHA @On=mE? =n@ ANFHAIIELA, =J lA=IJ BoH FHoCH=mmAHI =n@ ANFAHEAn?A@KIAHI. .oH EJI HolA En JDA oLAH=ll IOIJAm, )?mA moIJ HAIAm>lAI -M)+5 [5J=l'!]. 1J EI JHE?kO Jo ?omF=HA )?mA Jo -M)+5, JDoKCD, >A?=KIA JDAHA =HA m=nO LAHIEonI oB -M)+5 =n@, IEn?A EJ EI BKllO FHoCH=mm=>lA, -M)+5 ?=n En FHEn?EFlA @o =nOJDEnC )?mA @oAI. )lIo, )?mA EI mK?D OoKnCAH =n@ JDAHABoHA D=I noJ D=@ JDA JEmA Jo =?GKEHA =I m=nO BA=JKHAI. 6DA EIIKA JDAHABoHA EI lAII MD=J JDA IOIJAmI ?=n >A FHoCH=mmA@ Jo @o JD=n DoM JDAO =HA KIA@. 6DA -M)+5 LAHIEonI JD=J ?omA ?loIAIJ Jo )?mAߣI IJOlA =HA JDoIA JD=J D=LA >AAn ANJAn@A@ Jo FHoLE@A = FHoCH=mmEnC AnLEHonmAnJ, KIK=llO BoH = l=nCK=CA IK?D =I L152 [)llA' , LK?E@' ]. .oH HE?DnAII oB JDA ANEIJEnC EnJAHB=?A, JDAIA -M)+5 LAHIEonI =HA ?AHJ=EnlO IKFAHEoH Jo )?mA. On JDA oJDAH D=n@, )?mAߣI EnJAHB=?A MoHkI AGK=llO MAll =lHA=@O BoH = L=HEAJO oB l=nCK=CAI; BoH AN=mFlA, onA oB EJI moIJ AnJDKIE=IJE? KIAHI MoHkI =lmoIJAN?lKIELAlOEn5J=n@=H@ML,=l=nCK=CAnoJDEnClEkA+. 9DAHA )?mA AN?AlI EI En JDA ImooJDnAII oB EJI EnJAHB=?A. 7nJEl HA?AnJlO, -M)+5 @E@ noJ IKFFoHJ JDA moKIA AIFA?E=llO MAll, =n@ ALAn MEJD JDA l=JAIJ LAHIEon FHoLE@EnC BA=­ JKHAI IK?D =I ߢANJAnJIߣ JD=J ?=n >A FHoCH=mmA@ Jo >AD=LA mK?D lEkA )?mA ?omm=n@I, m=nO KIAHI @onߣJ >oJDAH Jo KFCH=@A. MoHAoLAH, En JDA LAHIEonI JD=J FHoLE@A ANJAnJI, moIJ-M)+5F=?k=CAI@onߣJJ=kA=@L=nJ=CAoBJDAm. 6DA moIJ EmFoHJ=nJ @EIJEn?JEon EI jKIJ JD=J -M)+5 EI BKn@=mAnJ=llO kAO>o=H@- >=IA@,MDElA)?mAEImoKIA->=IA@. 2AoFlA MDo JHO )?mA BEn@ EJ D=H@ Jo Co >=?k Jo JDAEH FHALEoKI AnLEHonmAnJ. )?mA =KJom=JAI Io mK?D JD=J Jo HAJKHn Jo = JH=@EJEon=l EnJAHB=?A EI Jo @H=M =JJAnJEon Jo JDA ANJH=MoHkEJHAGKEHAI. ­ ­

Concurrency in the implementation )?mA EI =>oKJ &, lEnAI oB ?o@A En )lAB, = ?on?KHHAnJ o>jA?J-oHEAnJA@ l=nCK=CA IOnJ=?JE?=llO IEmEl=H Jo + [)lAB]. )?mAߣI IJHK?JKHA EI = IAJ oB ?ommKnE?=JEnC FHo?AIIAI En = IEnClA =@@HAII IF=?A. OnA IK>IAJ oB JDA FHo?AIIAI @HELAI JDA @EIFl=O =n@ KIAH EnJAH­ B=?A, m=EnJ=EnEnC JDA MEn@oMI; oJDAH FHo?AIIAI BoHM=H@ moKIA =n@ kAO>o=H@ =?JELEJO =n@ EmFlAmAnJ JDA BElA IAHLAH EnJAHB=?A BoH ANJAHn=l FHoCH=mI. 6DA l=nCK=CA =n@ @AIECn MoHkA@ oKJ MAll; =I ANFl=EnA@ AlIAMDAHA [2EkA&', /=nI'!, 4AFFO'!], KIAH EnJAHB=?AI >KElJ MEJD ?on?KHHAnJ IOIJAmI ?=n =LoE@ JDA ?lKmIO JoF-lALAl ALAnJ looF JOFE?=l oB JH=@E­ JEon=lEnJAH=?JELAIOIJAmI. )n AN=mFlA oB JDA >AnABEJI oB JDA mKlJE-FHo?AII IJOlA EI JDA m=n=CAmAnJ oB JDA IJ=JA oB oFAn BElAI DAl@ >O ?lEAnJI oB JDA BElA IOIJAm EnJAHB=?A. 6DA FHo>lAm EI JD=J IomA 1/O HAGKAIJI, IK?D =I HA=@EnC JDA event BElA, m=O >lo?k EB no @=J= EI =L=El=>lA, =n@ JDA IAHLAH mKIJ m=EnJ=En JDA IJ=JA oB FoIIE>lO m=nO HAGKAIJI KnJEl @=J= =FFA=HI. .oH AN=mFlA, En 8½, = IEnClA-FHo?AII MEn@oM IOIJAm MHEJJAn En +, FAn@EnC HAGKAIJI MAHA GKAKA@ En = @=J= IJHK?JKHA =IIo?E=JA@ MEJD A=?D MEn@oM. )BJAH =?JELEJO En JDA MEn@oM JD=J mECDJ ?omFlAJA FAn@EnC 1/O, JDA @=J= IJHK?JKHA M=I I?=nnA@ BoH HAGKAIJI JD=J ?oKl@ noM BEnEID. 6DEI IJHK?JKHA @E@ noJ BEJ MAll MEJD JDA HAIJ oBJDAFHoCH=m=n@,MoHIA, HAGKEHA@ mAJE?KloKI ABBoHJ Jo CK=H=nJAA ?oHHA?J >AD=LEoH Kn@AH =ll ?on@EJEonI ?onIE@AH H=Mmo@A,HA=@IoBF=HJE=llEnAI,@AlAJEnC=MEn@oM,mKlJE>OJA?D=H=?JAHI,AJ?.. )?mA EnIJA=@ ?HA=JAI = nAM @A@E?=JA@ FHo?AII BoH A=?D 1/O HAGKAIJ. 6DEI FHo?AII ?ooH@En=JAI MEJD JDA HAIJ oB JDA IOIJAm KIEnC )lABߣI IOn?DHonoKI ?ommKnE?=JEon; EJI IJ=JA EmFlE?EJlO An?o@AI JDA IJ=JA oB JDA 1/O HAGKAIJ =n@ o>LE=JAI JDA nAA@ BoH GKAKEnC. 6DAF=II=CAoBJDAHAGKAIJJDHoKCD)?mAFHo?AA@I=IBolloMI. )?mA ?onJ=EnI = BElA IAHLAH FHo?AII, ., JD=J ANA?KJAI = read IOIJAm ?=ll Jo HA?AELA = 2l=n ' BElA FHoJo?ol '2 mAII=CA BHom JDA ?lEAnJ [)66' ]. 6DA ?lEAnJ >lo?kI KnJEl )?mA =nIMAHI JDA HAGKAIJ. . ?ommKnE?=JAI MEJD =n =llo?=JEon FHo?AII, M, Jo =?GKEHA =n o>jA?J oB JOFA Xfid ߢANA?KJEnC BE@ߣ; BE@ EI = '2 JAHm Jo Dol@ JDA HAGKAIJ. M IEJI En = looF HAFHo@K?A@ En .ECKHA  M=EJEnC BoH AEJDAH = HAGKAIJ BoH = nAM Xfid oH noJEBE?=JEon JD=J =n ANEIJEnC onA D=I BEnEIDA@ EJI J=Ik. 9DAn =n Xfid EI ?HA=JA@, =n =IIo?E=JA@ FHo­ ?AII, :, EI =lIo m=@A. M GKAKAI E@lA Xfids, =llo?=JEnC nAM onAI onlO MDAn JDA lEIJ EI AmFJO. 6DKI,JDAHAEI=lM=OI=FooloB Xfids,IomAANA?KJEnC,IomAE@lA. 6DA Xfid o>jA?J?onJ=EnI=?D=nnAl, Xfid.c,BoH?ommKnE?=JEonMEJD EJI FHo?AII; JDA KnF=?kA@ mAII=CA; =n@ IomA =IIo?E=JA@ BKn?JEonI, moIJlO ?oHHAIFon@EnC Jo '2 mAII=CAIIK?D=I Xfid.write JoD=n@lA='2MHEJAHAGKAIJ. 6DA BElA IAHLAH FHo?AII . F=HIAI JDA mAII=CA Jo IAA EJI n=JKHAߞoFAn, ?loIA, HA=@, MHEJA, AJ?. M=nO mAII=CAI, IK?D =I @EHA?JoHO lookKFI, ?=n >A D=n@lA@ EmmA@E=JAlO; JDAIA =HA HAIFon@A@ Jo @EHA?JlO =n@ ABBE?EAnJlO >O . MEJDoKJ EnLokEnC JDA Xfid, MDE?D EI JDAHABoHA m=EnJ=EnA@ KnJEl JDA nANJ mAII=CA. 9DAn = mAII=CA, IK?D =I = MHEJA Jo JDA @EIFl=O, HAGKEHAI JDA =JJAnJEon oB JDA m=En @EIFl=O FHo?AII =n@ EnJAHlo?kA@ =??AII Jo EJI @=J= IJHK?JKHAI, . An=>lAI : >O IAn@EnC = BKn?JEon FoEnJAH on Xfid.c. .oH AN=mFlA, EB JDAmAII=CAEI=MHEJA,.ANA?KJAI x−>c <−= Xfid.write; MDE?DIAn@IJDA=@@HAIIoB Xfid.write on Xfid.c,M=kEnCKF:. 6DA Xfid FHo?AII,:,ANA?KJAI=IEmFlAlooF: ­ !­

void Xfid.ctl(Xfid *x) { for(;;){ (*<−x−>c)(x); /* receive and execute message */ bflush(); /* synchronize bitmap display */ cxfidfree <−= x; /* return to free list */ } } 6DKI : MEll M=kA KF MEJD JDA =@@HAII oB = BKn?JEon Jo ?=ll DAHA Xfid.write =n@ ANA­ ?KJA EJ; on?A JD=J ?omFlAJAI, EJ HAJKHnI EJIAlB Jo JDA Fool oB BHAA FHo?AIIAI >O IAn@EnC EJI =@@HAII>=?kJoJDA=llo?=JoH. )lJDoKCD JDEI IAGKAn?A m=O IAAm ?omFlE?=JA@, EJ EI jKIJ = BAM lEnAI oB ?o@A =n@ EI En B=?J B=H IEmFlAH JD=n JDA m=n=CAmAnJ oB JDA 1/O GKAKAI En 8½. 6DAD=H@MoHkoBIOn­ ?DHonEz=JEon EI @onA >O JDA )lAB HKn JEmA IOIJAm. MoHAoLAH, JDA ?o@A MoHkA@ JDA BEHIJ JEmA,MDE?D?=nnoJ>AI=E@BoHJDA?o@AEn 8½.

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Acknowledgements 0oM=H@ 6HE?kAO, )?mAߣI BEHIJ KIAH, IKBBAHA@ >KCCO LAHIEonI CH=?ABKllO =n@ m=@A m=nO DAlFBKl IKCCAIJEonI. +DHEI .H=IAH FHoLE@A@ JDA nA?AII=HO EnIECDJ BoH JDA )?mA A@EJEnC?omm=n@I.

References [)lAB] 2. 9EnJAH>oJJom, ߢߢ)lAB L=nCK=CA 4ABAHAn?A M=nK=lߣߣ, Plan 9 Programmer’s Man- ual, )66*AllL=>oH=JoHEAI,MKHH=O0Ell,NJ, '' ;HALEIA@EnJDEILolKmA. [)llA' ] Allegro Common Lisp user Guide, Vol 2, +D=FJAH ", 6DA -m=?I-LEIF 1nJAHB=?A. M=H?D '' . [)66' ]2l=n'2HoCH=mmAHߣIm=nK=l,MKHH=O0Ell,NAMJAHIAO, '' . [.=H&'].=HJoom=nOFAoFlA,:6-4M ,M=II=?DKIAJJI1nIJEJKJAoB6A?DnoloCO, '&'. [/=nI'!] -m@An 4. /=nInAH =n@ JoDn 0. 4AFFO, ߢߢ) MKlJE-JDHA=@A@ 0ECDAH-oH@AH 7IAH 1nJAHB=?A 6oolkEJߣߣ,EnSoftware Trends, Volume 1, User Interface Software, *=II =n@ ,AM=n-@I.,JoDn9ElAO5onI ''!,FF.$ -&. [LK?E@' ]4E?D=H@5J=llm=n=n@LK?E@,1n?., Lucid GNU EMACS Manual, M=H?D '' . [2EkA&%] 4o> 2EkA, ߢߢ6DA 6ANJ -@EJoH samߣߣ, 5oBJM. - 2H=?J. =n@ -NF., NoL '&%, 8ol %  ,FF.& !-&"#;HAFHEnJA@EnJDEILolKmA. [2EkA&&] 4o> 2EkA, ߢߢ9En@oM 5OIJAmI 5DoKl@ *A 6H=nIF=HAnJߣߣ, +omF. 5OI., 5KmmAH '&&,8ol !,FF. %'- '$. [2EkA&'] 4o> 2EkA, ߢߢ) +on?KHHAnJ 9En@oM 5OIJAmߣߣ, +omF. 5OI., 5FHEnC '&', 8ol  , FF. !!- #!. [22669'!] 4o> 2EkA, ,=LA 2HAIoJJo, KAn 6DomFIon, 0oM=H@ 6HE?kAO, =n@ 2DEl 9EnJAH>oJ­ Jom, ߢߢ6DA 7IA oB N=mA 5F=?AI En 2l=n 'ߣߣ, OF. 5OI. 4AL., 8ol. %, No. , )FHEl ''!, FF. % -%$,HAFHEnJA@EnJDEILolKmA. [2EkA' ] 4o> 2EkA, ߢߢ&½, JDA 2l=n ' 9En@oM 5OIJAmߣߣ, 75-N1: 5KmmAH +onB. 2Ho?., N=ID­ LEllA,JKnA, '' ,FF. #%- $#,HAFHEnJA@EnJDEILolKmA. [2EkA' ] 4o> 2EkA, ߢߢ) MEnEm=lEIJ /lo>=l 7IAH 1nJAHB=?Aߣߣ, /H=FDE?I 1nJAHB=?A ߣ' 2Ho?., 8=n?oKLAH, '' , FF. & - '!. )n A=HlEAH LAHIEon =FFA=HA@ Kn@AH JDA I=mA JEJlA En 75-N1:5KmmAH+onB.2Ho?.,N=IDLEllA,JKnA, '' ,FF. $%- %'. [2EkA'!] 4o> 2EkA =n@ KAn 6DomFIon, ߢߢ0Allo 9oHl@ oH š±»·¼­Á± ºÌüµ oH ߣߣ,75-N1:9EnJAH+onB.2Ho?.,5=n,EACo, ''!,FF."!-#,HAFHEnJA@EnJDEILolKmA. [2HAI'!] ,=LA 2HAIoJJo =n@ 2DEl 9EnJAH>oJJom, ߢߢ6DA OHC=nEz=JEon oB NAJMoHkI En 2l=n 'ߣߣ,2Ho?.7IAnEN9EnJAH ''!,FF. % - &%,5=n,EACo,+),HAFHEnJA@EnJDEILolKmA. ­ #­

[4AEI' ]M=HJEn4AEIAH, The Oberon System, )@@EIon9AIlAO,NAM;oHk, '' . [4AFFO'!] JoDn 0. 4AFFO, ߢߢ+ML: ) DECDAH-oH@AH ?on?KHHAnJ l=nCK=CAߣߣ, 2Ho?. 51/­ 2L)Nߣ' +onB.on2HoCH=mmEnC,L=nC.,AIECn=n@1mFl.,JKnA, '' ,FF. '!-!#. [5?DA&$] 4o>AHJ 9. 5?DAEBlAH =n@ JEm /AJJOI, ߢߢ6DA : 9En@oM 5OIJAmߣߣ, )+M 6H=nI. on /H=FD.,8ol# ,FF.%'- '. [5J=l'!]4E?D=H@5J=llm=n, Gnu Emacs Manual, 9th edition, Emacs version 19.19, M16. [5MAE&$] ,=nEAl 5MAEnD=HJ, 2ollA ZAllMACAH, 4E?D=H@ *A=?D, =n@ 4o>AHJ 0=Cm=nn, ߢߢ) 5JHK?JKH=l 8EAM oB JDA +A@=H 2HoCH=mmEnC -nLEHonmAnJߣߣ, )+M 6H=nI. 2HoC. L=nC. =n@ 5OI.,8ol.&,No.",FF." '-"',O?J. '&$. [9EnJ'"], 2DElEF 9EnJAH>oJJom, ߢߢ)?E@: ) ,A>KCCAH >=IA@ on = L=nCK=CAߣߣ, 75-N1: 9EnJAH +onB.2Ho?.,5=n.H=n?EI?o,+), ''!,HAFHEnJA@EnJDEILolKmA. [9EHJ&'] N. 9EHJD =n@ J. /KJknA?DJ, ߢߢ6DA O>AHon 5OIJAmߣߣ, 5oBJM. - 2H=?. =n@ -NF., 5AF '&',8ol '',FF&#%-&'".