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ίϯύΠϥ͔Βඥղ͘
4XJGUNFUIPEEJTQBUDI
!LBUFJOPJHBLVLVO
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ࣗݾհ
w !LBUFJOPJHBLVLVO
w ૣҴాେֶߴֶӃ̏
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͍͖ͳΓͰ͕͢
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ΫΠζͰ͢
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class Cat {
func bark() -> String {
return "ʹΌΜ"
}
}
class Dog {
func bark() -> String {
return "ΘΜ"
}
}
let cat = Cat()
let dog = unsafeBitCast(cat, to: Dog.self)
print(dog.bark())
2Կ͕ग़ྗ͞ΕΔͰ͠ΐ͏ʁ
ʹΌΜPSΘΜ
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class Cat {
func bark() -> String {
return "ʹΌΜ"
}
}
class Dog {
func bark() -> String {
return "ΘΜ"
}
}
let cat = Cat()
let dog = unsafeBitCast(cat, to: Dog.self)
print(dog.bark())
2Կ͕ग़ྗ͞ΕΔͰ͠ΐ͏ʁ
"ΘΜ
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ʮΘΜʯ
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ࠓ͢͜ͱ
w .FUIPE%JTQBUDIͷΈ
w ࠷దԽͷΈ
w ύϑΥʔϚϯε
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2.FUIPEEJTQBUDIͱʁ
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2.FUIPEEJTQBUDIͱʁ
"ϝιου͕ݺͼग़͞ΕΔ࣌ʹɺ
࣮ࡍʹͲͷϝιουΛ࣮ߦ͢Δ͔ΛܾΊΔػߏ
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No content
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class Animal {
func bark() {
print("ΞχϚϧͰ͢")
}
}
class Cat: Animal {
override func bark() {
print("ʹΌΜ")
}
}
func callAnimalBark(_ animal: Animal) {
animal.bark()
}
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class Animal {
func bark() {
print("ΞχϚϧͰ͢")
}
}
class Cat: Animal {
override func bark() {
print("ʹΌΜ")
}
}
func callAnimalBark(_ animal: Animal) {
animal.bark() // ΞχϚϧͰ͢ or ʹΌΜ
}
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class Animal {
func bark() {
print("ΞχϚϧͰ͢")
}
}
class Cat: Animal {
override func bark() {
print("ʹΌΜ")
}
}
func callAnimalBark(_ animal: Animal) {
animal.bark() // ΞχϚϧͰ͢ or ʹΌΜ
}
࣮ߦ͞ΕΔϝιουͲͬͪʁʁ
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.FUIPE%JTQBUDIͷύλʔϯ
w 4UBUJD%JTQBUDI
w ݺͼग़͢ϝιουΛίϯύΠϧ࣌ʹܾΊΔ
w %ZOBNJD%JTQBUDI
w ݺͼग़͢ϝιουΛ࣮ߦ࣌ʹܾΊΔ
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4UBUJD%JTQBUDI
w ؔ
w ܕͷϝιου
w FYUFOTJPOʹॻ͍ͨϝιου
w pOBMͳϝιου
struct S {
func foo() {}
}
let s = S()
s.foo()
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4UBUJD%JTQBUDI
struct S {
func foo() {}
}
let s = S()
s.foo()
ಉ͡γάωνϟͷϝιου͕ଘࡏ͠ͳ͍
w ؔ
w ܕͷϝιου
w FYUFOTJPOʹॻ͍ͨϝιου
w pOBMͳϝιου
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%ZOBNJD%JTQBUDI
w $MBTTͷϝιου
w 1SPUPDPMͷϝιου
protocol Animal {
func foo()
}
struct Cat: Animal {
func foo() {}
}
func callFoo(_ animal: T) {
animal.foo()
}
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w $MBTTͷϝιουΦʔόʔϥΠυ
w 1SPUPDPMͷϝιουෳͷܕ͕४ڌ
%ZOBNJD%JTQBUDI
protocol Animal {
func foo()
}
struct Cat: Animal {
func foo() {}
}
func callFoo(_ animal: T) {
animal.foo()
}
ಉ͡γάωνϟͷϝιου͕ෳଘࡏ͢Δ
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.FUIPE%JTQBUDIͷύλʔϯ
w 4UBUJD%JTQBUDI
w ݺͼग़͢ϝιουΛίϯύΠϧ࣌ʹܾΊΔ
w %ZOBNJD%JTQBUDI
w ݺͼग़͢ϝιουΛ࣮ߦ࣌ʹܾΊΔ
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.FUIPE%JTQBUDIͷύλʔϯ
w 4UBUJD%JTQBUDI
w ݺͼग़͢ϝιουΛίϯύΠϧ࣌ʹܾΊΔ
w %ZOBNJD%JTQBUDI
w ݺͼग़͢ϝιουΛ࣮ߦ࣌ʹܾΊΔ
w 75BCMF
w 8JUOFTT5BCMF
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75BCMF
w Ծؔςʔϒϧ͔ΒϝιουΛ୳ࡧ͢Δ%JTQBUDIํࣜ
w ΫϥεͷϝιουΛݺͼग़࣌͢ʹ͏
w ΠϯελϯεͷϝλσʔλʹຒΊࠐ·ΕΔ
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func Animal.bark()
*Animal.bark
75BCMFGPS"OJNBM
class Animal {
func bark() {}
}
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func Animal.bark()
*Animal.bark
75BCMFGPS$BU
*Animal.bark
75BCMFGPS"OJNBM
class Animal {
func bark() {}
}
class Cat: Animal {
}
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func Cat.foo()
func Animal.bark()
*Animal.bark
*Animal.bark
*Cat.foo
75BCMFGPS"OJNBM
75BCMFGPS$BU
class Animal {
func bark() {}
}
class Cat: Animal {
func foo() {}
}
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class Animal {
func bark() {}
}
class Cat: Animal {
override func bark() {}
func foo() {}
}
75BCMFGPS$BU
func Animal.bark()
75BCMFGPS"OJNBM
*Animal.bark
*Animal.bark
*Cat.foo
func Cat.bark()
func Cat.foo()
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8JUOFTT5BCMF
w Ծؔςʔϒϧ͔ΒϝιουΛ୳ࡧ͢Δ%JTQBUDIํࣜ
w ϓϩτίϧͷϝιουΛݺͼग़࣌͢ʹ͏
w ϓϩτίϧͷ४ڌ͝ͱʹఆٛ͞ΕΔ
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protocol Animal {
func bark()
}
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protocol Animal {
func bark()
}
struct Dog: Animal {
func bark() {}
}
8JUOFTT5BCMFGPS"OJNBM
JODPOGPSNBODF%PH
*Animal.bark
func Animal.bark(dog) {
Dog.bark(dog)
}
8JUOFTTNFUIPEGPS"OJNBM
JODPOGPSNBODF%PH
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ʮΘΜʯ
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class Cat {
func bark() -> String {
return "ʹΌΜ"
}
}
class Dog {
func bark() -> String {
return “ΘΜ"
}
}
let cat = Cat()
let dog = unsafeBitCast(cat, to: Dog.self)
print(dog.bark())
ϝϞϦϨΠΞτมߋ͞Εͳ͍
ࢀর͢ΔVTableมΘΒͳ͍
Catͷςʔϒϧ͕ࢀর͞ΕΔ
ʮʹΌΜʯ͕ग़ྗ͞ΕΔͣʂ
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͔͠͠ɺ
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class Cat {
func bark() -> String {
return "ʹΌΜ"
}
}
class Dog {
func bark() -> String {
return "ΘΜ"
}
}
let cat = Cat()
let dog = unsafeBitCast(cat, to: Dog.self)
print(dog.bark()) // ΘΜ
ʮΘΜʯ
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No content
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࠷దԽΛΦϑʹͯ͠ΈΔ
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$ swiftc -frontend -c -primary-file animal.swift
$ swiftc animal.o
$ ./animal
ʹΌΜ
ʮʹΌΜʯ
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࠷దԽͷաఔʹԿ͔͋Γͦ͏
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%FWJSUVBMJ[F
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%FWJSUVBMJ[F
w 4*-0QUJNJ[FSͷ࠷దԽύε
w %ZOBNJD%JTQBUDIΛ4UBUJD%JTQBUDIʹ࠷దԽ͢Δ
w ίϯύΠϧ࣌ͷܕใ͔ΒϝιουΛ̍ͭʹܾΊΔ
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75BCMFͷ࠷దԽ
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USZ%FWJSUVBMJ[F"QQMZ
auto &M = FAS.getModule();
auto Instance = stripUpCasts(CMI->getOperand());
auto ClassType = Instance->getType();
...
if (isEffectivelyFinalMethod(FAS, ClassType, CD, CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE,
true /*isEffectivelyFinalMethod*/);
if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(),
CMI->getModule(),
CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE);
if (auto ExactTy = getExactDynamicType(CMI->getOperand(), CMI->getModule(),
CHA)) {
if (ExactTy == CMI->getOperand()->getType())
return tryDevirtualizeClassMethod(FAS, CMI->getOperand(), ORE);
}
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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USZ%FWJSUVBMJ[F"QQMZ
auto &M = FAS.getModule();
auto Instance = stripUpCasts(CMI->getOperand());
auto ClassType = Instance->getType();
...
if (isEffectivelyFinalMethod(FAS, ClassType, CD, CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE,
true /*isEffectivelyFinalMethod*/);
if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(),
CMI->getModule(),
CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE);
if (auto ExactTy = getExactDynamicType(CMI->getOperand(), CMI->getModule(),
CHA)) {
if (ExactTy == CMI->getOperand()->getType())
return tryDevirtualizeClassMethod(FAS, CMI->getOperand(), ORE);
}
Πϯελϯεͷ࣮ߦ࣌ͷܕ͕੩తʹܾఆͰ͖Δύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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%FWJSUVBMJ[FGPS75BCMF
class Animal {
func bark() {}
}
class Cat: Animal {
override func bark() {}
}
let animal: Animal = Cat() // ΠχγϟϥΠβ͔Β࡞ͬͯΔͷͰCatܕ
animal.bark()
Πϯελϯεͷ࣮ߦ࣌ͷܕ͕੩తʹܾఆͰ͖Δύλʔϯ
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USZ%FWJSUVBMJ[F"QQMZ
auto &M = FAS.getModule();
auto Instance = stripUpCasts(CMI->getOperand());
auto ClassType = Instance->getType();
...
if (isEffectivelyFinalMethod(FAS, ClassType, CD, CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE,
true /*isEffectivelyFinalMethod*/);
if (auto Instance = getInstanceWithExactDynamicType(CMI->getOperand(),
CMI->getModule(),
CHA))
return tryDevirtualizeClassMethod(FAS, Instance, ORE);
if (auto ExactTy = getExactDynamicType(CMI->getOperand(), CMI->getModule(),
CHA)) {
if (ExactTy == CMI->getOperand()->getType())
return tryDevirtualizeClassMethod(FAS, CMI->getOperand(), ORE);
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
if (CD && CD->isFinal())
return true;
const DeclContext *DC = AI.getModule().getAssociatedContext();
auto *CMI = cast(AI.getCallee());
if (!calleesAreStaticallyKnowable(AI.getModule(), CMI->getMember()))
return false;
auto *Method = CMI->getMember().getAbstractFunctionDecl();
if (!Method->isOverridden())
return true;
...
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
if (CD && CD->isFinal())
return true;
const DeclContext *DC = AI.getModule().getAssociatedContext();
auto *CMI = cast(AI.getCallee());
if (!calleesAreStaticallyKnowable(AI.getModule(), CMI->getMember()))
return false;
auto *Method = CMI->getMember().getAbstractFunctionDecl();
if (!Method->isOverridden())
return true;
...
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
if (CD && CD->isFinal())
return true;
const DeclContext *DC = AI.getModule().getAssociatedContext();
auto *CMI = cast(AI.getCallee());
if (!calleesAreStaticallyKnowable(AI.getModule(), CMI->getMember()))
return false;
auto *Method = CMI->getMember().getAbstractFunctionDecl();
if (!Method->isOverridden())
return true;
...
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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DBMMFFT"SF4UBUJDBMMZ,OPXBCMF
bool swift::calleesAreStaticallyKnowable(SILModule &M, SILDeclRef Decl) {
...
switch (AFD->getEffectiveAccess()) {
case AccessLevel::Open:
return false;
case AccessLevel::Public:
if (isa(AFD)) {
auto *ND = AFD->getDeclContext()->getSelfNominalTypeDecl();
if (ND->getEffectiveAccess() == AccessLevel::Open)
return false;
}
case AccessLevel::Internal:
return M.isWholeModule();
case AccessLevel::FilePrivate:
case AccessLevel::Private:
return true;
}
}
ϝιουΛ੩తʹܾఆͰ͖Δύλʔϯ
MJC4*-0QUJNJ[FS6UJMT-PDBMDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
if (CD && CD->isFinal())
return true;
const DeclContext *DC = AI.getModule().getAssociatedContext();
auto *CMI = cast(AI.getCallee());
if (!calleesAreStaticallyKnowable(AI.getModule(), CMI->getMember()))
return false;
auto *Method = CMI->getMember().getAbstractFunctionDecl();
if (!Method->isOverridden())
return true;
...
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
...
if (!Method->isOverridden())
return true;
ClassHierarchyAnalysis::ClassList Subs;
getAllSubclasses(CHA, CD, ClassType, AI.getModule(), Subs);
auto *ImplMethod = CD->findImplementingMethod(Method);
for (auto S : Subs) {
auto *ImplFD = S->findImplementingMethod(Method);
if (ImplFD != ImplMethod)
return false;
}
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
...
if (!Method->isOverridden())
return true;
ClassHierarchyAnalysis::ClassList Subs;
getAllSubclasses(CHA, CD, ClassType, AI.getModule(), Subs);
auto *ImplMethod = CD->findImplementingMethod(Method);
for (auto S : Subs) {
auto *ImplFD = S->findImplementingMethod(Method);
if (ImplFD != ImplMethod)
return false;
}
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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JT&⒎FDUJWFMZ'JOBM.FUIPE
static bool isEffectivelyFinalMethod(FullApplySite AI,
SILType ClassType,
ClassDecl *CD,
ClassHierarchyAnalysis *CHA) {
...
if (!Method->isOverridden())
return true;
ClassHierarchyAnalysis::ClassList Subs;
getAllSubclasses(CHA, CD, ClassType, AI.getModule(), Subs);
auto *ImplMethod = CD->findImplementingMethod(Method);
for (auto S : Subs) {
auto *ImplFD = S->findImplementingMethod(Method);
if (ImplFD != ImplMethod)
return false;
}
return true;
}
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
MJC4*-0QUJNJ[FS6UJMT%FWJSUVBMJ[FDQQ
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0WFSSJEF͞ΕͭͭΠϯελϯε͕
ͦͷαϒΫϥεʹͳΓಘͳ͍߹
class Cat {
func bark() {}
}
enum Tama {}
enum Kuro {}
class TamaCat: Cat {
override func bark() {}
}
func callBark(cat: Cat) {
cat.bark()
}
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class Cat {
func bark() {}
}
enum Tama {}
enum Kuro {}
// CatͷαϒλΠϓͰͳ͍
class TamaCat: Cat {
override func bark() {}
}
func callBark(cat: Cat) {
cat.bark()
}
0WFSSJEF͞ΕͭͭΠϯελϯε͕
ͦͷαϒΫϥεʹͳΓಘͳ͍߹
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JT&⒎FDUJWFMZ'JOBM.FUIPE
ϝιου͕z࣮࣭pOBMzͳύλʔϯ
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ʮΘΜʯ
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class Cat {
func bark() -> String {
return “ʹΌΜ"
}
}
class Dog {
func bark() -> String {
return "ΘΜ"
}
}
let cat = Cat()
let dog = unsafeBitCast(cat, to: Dog.self)
print(dog.bark()) // ΘΜ
࠷దԽ͋Γͷ߹
Dog.barkϝιουnon-final
ΦʔόʔϥΠυ͞Ε͍ͯͳ͍ͷͰ”࣮࣭final”
dog.bark()͕Static Dispatchʹ࠷దԽ͞ΕΔ
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࠷దԽͳ͠ͷ߹
class Cat {
func bark() -> String {
return “ʹΌΜ"
}
}
class Dog {
func bark() -> String {
return "ΘΜ"
}
}
let cat = Cat()
let dog = unsafeBitCast(cat, to: Dog.self)
print(dog.bark()) // ʹΌΜ
Whole Module࠷దԽ͕Φϑ
ϞδϡʔϧͰΦʔόʔϥΠυ͞ΕΔՄೳੑ͕͋Δ
ΠϯελϯεͷϝλσʔλͷVTable͔Β
Dynamic Dispatch͢Δ
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%JTQBUDI
1FSGPSNBODF
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LBUFJOPJHBLVLVO%JTQBUDI#FODINBSL
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3VOUJNF1FSGPSNBODF
/VNCFSPGEJTQBUDI
$165JNF
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·ͱΊ
w %ZOBNJD%JTQBUDIΓ͍
w pOBMQSJWBUFͪΌΜͱޮՌ͕͋Δ
w ͕ɺίϯύΠϥ͕ݡ͍ͷͰେମ4UBUJD%JTQBUDIʹͳΔ
w ίϯύΠϥΛಡΊ4XJGUͷڍಈ͕͔͓ͬͯ͠Ζ͍
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w IUUQTHJUIVCDPNBQQMFTXJGUCMPCNBTUFSEPDT4*-STU
w IUUQTHJUIVCDPNBQQMFTXJGUCMPCNBTUFSEPDT
0QUJNJ[BUJPO5JQTSTUSFEVDJOHEZOBNJDEJTQBUDI
w !PNPDIJNFUBSV4XJGUͷδΣωϦοΫͳϓϩτίϧͷมͳͥ࡞Εͳ͍ͷ͔ɺ
ίϯύΠϧޙͷதؒݴޠΛݟͯߟ͑ͨ
w IUUQTRJJUBDPNPNPDIJNFUBSVJUFNTCFFBBBFGB
ࢀߟ