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Copy pathclass.cpp
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2410 lines (1844 loc) · 69.6 KB
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/*
# class
*/
#include "common.hpp"
#include "no_base_no_member.hpp"
class Empty {};
/**
This class has a compiler supplied default constructor.
*/
class ImplicitDefaultCtor {
public:
int i;
std::string s;
};
/**
This class has no default constructor since another constructor was defined.
*/
class NoDefaultCtor {
public:
NoDefaultCtor(int i) : i(i) {}
int i;
};
/**
This class defines a default constructor since it will also provide a non default one.
*/
class ExplicitDefaultCtor {
public:
int i;
ExplicitDefaultCtor(){}
ExplicitDefaultCtor(int i) : i(i){}
};
/**
This class uses its default copy constructor and assign operator.
*/
class DefaultCopyAssignCtor {
public:
int i;
DefaultCopyAssignCtor() : i(0) {}
DefaultCopyAssignCtor(int i) : i(i) {}
};
/**
This politically incorrect clas does not implement the equality == operator.
*/
class NoEquality {
public:
NoEquality() : i(0) {}
int i;
};
#if __cplusplus >= 201103L
class CtorFromCtor {
public:
std::vector<int> v;
/**
This constructor does the default which is calling the parent's default constrctor before its own.
An error would be generated if the parent class has no defalt constructor.
*/
CtorFromCtor(int i) : v(1,i) {}
/**
This constructor calls another constructor with arguments before running its own.
*/
CtorFromCtor(int i, int j) : CtorFromCtor(i) {
v.push_back(j);
}
};
#endif
#if __cplusplus >= 201103L
/**
This class exemplifies the `= default` syntax.
*/
class DefaultKeyword {
public:
/**
This is an explicitly defaulted constructor.
*/
DefaultKeyword() = default;
/**
This is an explicitly defaulted copy constructor.
*/
DefaultKeyword(const DefaultKeyword&) = default;
/**
This is an explicitly defaulted assignment operator.
*/
DefaultKeyword & operator=(const DefaultKeyword&) = default;
~DefaultKeyword() = default;
// ERROR: Not possible because the default constructor must take no arguments.
//DefaultKeyword(int i) = default;
// With the default keyword it is possible to have other
// constructors besides the Implicitly defined constructor.
DefaultKeyword(int i, std::string s) : i(i), s(s) {}
/**
ERROR: Cannot default anything other than:
- constructors
- destructors
- copy
- assignment
*/
//void f() = default;
int i;
std::string s;
};
/**
This class exemplifies the `= delete` syntax.
*/
class DeleteKeyword {
public:
DeleteKeyword() = delete;
DeleteKeyword(int i) : i(i) {}
DeleteKeyword(const DeleteKeyword&) = delete;
DeleteKeyword & operator=(const DeleteKeyword&) = delete;
/**
With this, the code would compile, but it would not be possible
to create any instances of this class, since at some point the destructor
would have to be called!
*/
//~DeleteKeyword() = delete;
/* It is possible to delete any function. */
void f() = delete;
int i;
};
#endif
/**
This class has an implicit default constructor.
*/
class UniformInitializationImplicitCtor {
public:
int i;
int j;
};
/**
This class has an explicit default constructor,
and no constructor that takes 2 ints.
*/
class UniformInitializationExplicitCtor {
public:
int i;
int j;
UniformInitializationExplicitCtor() : i(0), j(0) {}
};
/**
This class has a constructor that takes 2 ints.
*/
class UniformInitializationCtor2 {
public:
int i;
int j;
UniformInitializationCtor2(int i, int j) : i(i), j(j+1) {}
bool operator==(const UniformInitializationCtor2& other) {return this->i == other.i && this->j == other.j;}
};
int UniformInitializationCtor2Func(UniformInitializationCtor2 o){
return o.i + o.j;
}
class UniformInitializationList {
public:
int i;
int j;
UniformInitializationList(int i, int j) : i(i), j(j+1) {}
UniformInitializationList(std::initializer_list<int> list){
i = *(list.begin());
j = *(list.begin() + 1);
}
};
#if __cplusplus >= 201103L
/**
This class has an `Initializer_list` constructor.
*/
class InitializerListCtor {
public:
std::vector<int> v;
InitializerListCtor(std::initializer_list<int> list) {
for (auto& i : list)
v.push_back(i);
}
InitializerListCtor(int before, std::initializer_list<int> list, int after) {
v.push_back(before + 1);
for (auto& i : list)
v.push_back(i);
v.push_back(after - 1);
}
};
#endif
class MemberConstructorTest {
public:
NoBaseNoMember0 member0;
NoBaseNoMember1 member1;
MemberConstructorTest(){callStack.push_back("MemberConstructorTest::MemberConstructorTest()");}
~MemberConstructorTest(){callStack.push_back("MemberConstructorTest::~MemberConstructorTest()");}
void method(){callStack.push_back("MemberConstructorTest::method()");}
};
class Member {
public:
Member(){callStack.push_back("Member::Member()");}
Member(int i){callStack.push_back("Member::Member(int)");}
~Member(){callStack.push_back("Member::~Member()");}
void method() {callStack.push_back("Member::method()");}
int i;
};
class Nested {
public:
Nested() { callStack.push_back("Nested::Nested()"); }
};
/*
# this
Magic value that points to the current object.
It is implemented by the compiler by passing `this` as the first argument
of every non-static function of the class.
This is noticeable when doing operator overload:
*/
class Base {
public:
/// Best to put typedefs on top of class so def will go for entire class.
typedef int NESTED_INT;
Base() : i(0), j(1) {
callStack.push_back("Base::Base()");
// BAD: same as list init, except if i is an object
// to keep uniform style, always use list init
//this->i=0;
//this->j=1;
// ERROR: ic is const. must be initialized in list initialization.
//ic=0;
// BAD: compiles but infinite loop!
//Base b;
}
/*
# Initialization list
Initialization lists have 4 main uses:
1) avoid calling member object constructor and copy separately
2) initializing base classes with non default constructors
3) initializing const elements
4) initializing member references &
# Delegating constructors
C++11 also makes it possible to call a different constructor of the current
class on the initialization list. This feature is called delegating constructors.
*/
Base(int i, int j) : i(i), j(j) {
callStack.push_back("Base::Base(int, int)");
}
// ERROR: constructor cannot be virtual:
//virtual Base(float f){}
#if __cplusplus >= 201103L
/// C++11 initialize array/std containers in list initializtion.
Base(float f) : i(0), fs4{f,f,f,f}, vi{0,1,2,3} {
callStack.push_back("Base::Base(float)");
}
#endif
virtual ~Base() {
callStack.push_back("Base::~Base()");
}
void method() {
callStack.push_back("Base::method()");
int i = iAmbiguous;
i = iStatic;
i = iConstStatic;
}
void constMethod() const;
void constMethod(int *&) const;
void methodAmbiguous(){callStack.push_back("Base::methodAmbiguous()");}
// virtual: decides on runtime based on object type
// http://stackoverflow.com/questions/2391679/can-someone-explain-c-virtual-methods
virtual void virtualMethod(){callStack.push_back("Base::virtualMethod()");}
virtual Base* covariantReturn() {
callStack.push_back("Base:covariantReturn()");
return new Base;
}
virtual void covariantArg(Base* b) {
callStack.push_back("Base:covariantArg()");
}
int i, j;
// ERROR: cannot initialize here.
//int initialized_outside_ctor = 0;
int iPublic;
int iAmbiguous;
int* is;
float fs4[4];
std::vector<int> vi;
mutable int mutableI;
// ERROR: statics can be changed in const functions by default.
//static mutable int staticMutableI;
/*
BAD every class must have an assigment operator.
But then, assigment does something like this->ic = other->ic
You could redefine the assigment, but still in your new definition ic cannot be changed.
<http://stackoverflow.com/questions/634662/non-static-const-member-cant-use-default-assignment-operator>
*/
// # static
static void staticMethod();
// ERROR: static cannot be const.
//static void staticMethod() const;
static int iStatic;
// Concflicts with static int.
//int iStatic;
// OK: because const static integral type
const static int iConstStatic = 0;
/*
# member initialization outside of constructor
*/
const int iConstInit = 0;
// ERROR: cannot initialize here unless const.
//static int iStatic = 0;
// ERROR: non-integral type.
//const static float fConstStatic = 0.0;
const static Member member;
// OK: why ok?
const static Member member2;
//default constructor works
//const static NoBaseNoMember(1);
/*
ERROR: non integral type must be init outside.
why integral types are an exception:
<http://stackoverflow.com/questions/13697265/static-const-double-cannot-have-an-in-class-initializer-why-is-it-so>
*/
class Nested {
public:
Nested() {
callStack.push_back("Base::Nested::Nested()");
int i = privateStaticInt;
//you have private access
}
Member m;
};
class Nested2 {
public:
Nested2() {
callStack.push_back("Base::Nested2::Nested2()");
}
Nested innerIn;
//inner one
::Nested innerOut;
//outter one
};
protected:
int iProtected;
void fProtected(){callStack.push_back("Base::fProtected()");}
private:
int iPrivate;
void fPrivate(){callStack.push_back("Base::fPrivate()");}
const static int privateStaticInt = 1;
typedef int PRIVATE_NESTED_INT;
};
/*
# friend
Allow external functions and other classes to access private memebers of this class.
Friendship is not automatically reflexive nor transitive.
One case in which friendship may be unavoidable is for operator overload of operators which cannot
be class members and must be implemented as external functions such as `operator<<`.
This happens because of the nature of operators, which may force them to be implemented outside the class.
<http://www.cplusplus.com/doc/tutorial/inheritance/>
# friend and templates
Things get complicated when friends and template classes interact:
<http://publib.boulder.ibm.com/infocenter/lnxpcomp/v8v101/index.jsp?topic=%2Fcom.ibm.xlcpp8l.doc%2Flanguage%2Fref%2Ffriends_and_templates.htm>
*/
class FriendOfFriend;
class Friend {
public:
friend class FriendOfFriend;
Friend(int i) : i(i) {}
int getI(){return this->i;}
//this declaration says that `friendGetIPrivate(Base)` is a friend of this class.
//It will be defined outside the class.
friend int friendGetI(Friend f);
/* The same as friendGetI, but also defined inside the class. */
friend int friendGetIInnerDefine(Friend f) {
// ERROR: it is as if this were a friend external function, so there is no `this`.
//return this->i;
return f.i;
}
int getFriendI(FriendOfFriend f);
private:
int i;
void privateMethod(){};
};
/* cannot use the word friend here */
int friendGetI(Friend f){
// ERROR: this is a non-member function, so no `this`.
//return this->i;
return f.i;
}
class FriendOfFriend {
public:
FriendOfFriend(int i) : i(i) {}
int getFriendI(Friend f){return f.i;}
void callFriendPrivateMethod(Friend f){f.privateMethod();}
private:
int i;
};
// ERROR: friend used outside class.
//friend int friendGetI(Friend f){return f.i;}
// ERROR: not a friend because reflexivity is not automatic.
//int Friend::getFriendI(FriendOfFriend f) {return f.i;}
/*
# const method
Methods that cannot change the data of their object.
Inner workings: the hidden *this* pointer is downgraded to `const X*` when passing it to the function:
void method() const
becomes:
void method(const Class* this) const
instead of:
void method(Class* this) const
*/
void Base::constMethod() const {
// ERROR: cant assign member in const func.
//this->i = 2;
// ERROR: cant call non const method inside const method!
// as that method could change the object
//this->member.method();
// ERROR: cant assign member of a member in const method.
//this->member.i = 1;
/*
# mutable
OK
Mutable allows you to change it even in a const method.
Application to multithreading:
http://stackoverflow.com/questions/105014/does-the-mutable-keyword-have-any-purpose-other-than-allowing-the-variable-to
*/
this->mutableI = 1;
// Static changes can still be done.
this->iStatic = 1;
callStack.push_back("Base::constMethod()");
{
// ERROR: conversion from const Base* to Base*.
//Base* this2 = this;
const Base* this2const = this;
}
}
// ERROR must not ommit the const here either.
//void Base::constMethod () {}
/*
Cannot return a non const pointer from a const method, since this is const,
so all members are also const.
*/
void Base::constMethod(int *& ip) const {
// ERROR: invalid conversion.
//ip = &this->iPrivate;
}
int Base::iStatic = 0;
void Base::staticMethod() {
callStack.push_back("Base::staticMethod()");
// ERROR: no this!
//int i = this->i;
// OK: ok to use static vars
int i = iStatic;
}
// ERROR: static linkage, like in C static.
// meaning func only visible from current translational unit
//static void staticMethod()
// Must come outside
const Member Base::member2 = Member(1);
// ERROR: must be declared inside.
//int Base::k;
// # virtual
class BaseAbstract {
public:
// Can be called in derived classes init list.
BaseAbstract(){}
virtual ~BaseAbstract() {}
void method() { callStack.push_back("BaseAbstract::method()"); }
void methodAmbiguous() {callStack.push_back("BaseAbstract::methodAmbiguous()"); }
virtual void virtualMethod() { callStack.push_back("BaseAbstract::virtualMethod()"); }
virtual void pureVirtual() = 0;
// BAD: won't work: must implement on derived class only.
//virtual void pureVirtualImplementedOtherBase() = 0;
int i;
int iAmbiguous;
private:
// This can/must still be implemented on the base class, even if private!
virtual void privatePureVirtual() = 0;
// How private pure virtual can be useful.
void usefulPrivatePureVirtual() {
callStack.push_back("common before");
privatePureVirtual();
callStack.push_back("common after");
}
};
class PureVirtualImplementedOtherBase {
public:
void pureVirtual() {
callStack.push_back("PureVirtualImplementedOtherBase::pureVirtual()");
}
private:
void privatePureVirtual() {
callStack.push_back("PureVirtualImplementedOtherBase::privatePureVirtual()");
}
};
class DerivedAbtractAndImplementator : BaseAbstract, PureVirtualImplementedOtherBase {
//public:
//void pureVirtual()
//{
//callStack.push_back("PureVirtualImplementedOtherBase::pureVirtual()");
//}
//private:
//void privatePureVirtual()
//{
//callStack.push_back("PureVirtualImplementedOtherBase::privatePureVirtual()");
//}
};
class InheritOverloadBase {
public:
void overload(){}
void not_overload(){}
};
class InheritOverloadDerived : public InheritOverloadBase {
public:
// `using` is required, or f(int) hides `f()`.
using InheritOverloadBase::overload;
void overload(int i) {
overload();
// This one does not reqire using becase it is not overloaded.
not_overload();
}
};
#if __cplusplus >= 201103L
class InheritingCtorBase {
public:
int i;
InheritingCtorBase() : i(0) {}
InheritingCtorBase(int i) : i(i) {}
};
class InheritingCtorDerived : public InheritingCtorBase {
public:
// Will define InheritingCtorDerived(int) and the copy constructor.
using InheritingCtorBase::InheritingCtorBase;
};
#endif
class VirtualFromCtorBase {
public:
int i;
int j;
VirtualFromCtorBase() {
// Calls base::a, not derived::a
this->i = a();
// LINKER ERROR: undefined reference to b().
//j = b();
}
virtual int a() { return 0; }
virtual int b() = 0;
};
class VirtualFromCtorDerived : public VirtualFromCtorBase {
public:
virtual int a() { return 1; }
virtual int b() { return 10; }
};
class VirtualFromCtor2PhaseBase {
public:
int i;
int j;
VirtualFromCtor2PhaseBase() {}
void init() {
this->i = a();
this->j = b();
}
virtual int a() { return 0; }
virtual int b() = 0;
};
class VirtualFromCtor2PhaseDerived : public VirtualFromCtor2PhaseBase {
public:
VirtualFromCtor2PhaseDerived() { init(); }
virtual int a() { return 1; }
virtual int b() { return 10; }
};
class MultipleInheritanceConflictBase1 {
public:
const static int is = 1;
int i;
void f(){}
};
class MultipleInheritanceConflictBase2 {
public:
const static int is = 2;
int i;
void f(){}
};
class MultipleInheritanceConflictDerived :
MultipleInheritanceConflictBase1,
MultipleInheritanceConflictBase2
{};
class BaseProtected {
public:
BaseProtected(){callStack.push_back("BaseProtected::BaseProtected()");}
BaseProtected(int i){callStack.push_back("BaseProtected::BaseProtected(int)");}
~BaseProtected(){callStack.push_back("BaseProtected::~BaseProtected()");}
};
class BasePrivate {
public:
BasePrivate(){callStack.push_back("BasePrivate::BasePrivate()");}
BasePrivate(int i){callStack.push_back("BasePrivate::BasePrivate(int)");}
~BasePrivate(){callStack.push_back("BasePrivate::~BasePrivate()");}
};
class Derived : private BasePrivate {};
class Class :
public Base,
//public Base, // ERROR: duplicate.
//public Derived, // WARN: cannot use BasePrivate inside: ambiguous.
protected BaseProtected,
private BasePrivate,
public BaseAbstract
{
public:
/*
calls base constructors first
*/
Class() : i(0), z(1) {
callStack.push_back("Class::Class()");
}
Class(int i) : i(i), z(0) {
callStack.push_back("Class::Class(int)");
}
/*
calls specific base constructors instead of default ones
another application os initialization lists
works even if the BaseAbstract class is abstract!
this is the only place you can do that: init list of derived classes
*/
Class(int i, int z) : Base(i,z), BaseProtected(i), BasePrivate(i), BaseAbstract(), i(i), z(z) {
callStack.push_back("Class::Class(int, int)");
}
// WARN: BaseAbstract will be init after TODO ?
//Class() : BaseAbstract(), Base(i,z), BaseProtected(i), BasePrivate(i), i(i), z(z)
//try catch in case base constructor can throw exceptions
Class(int i, int j, int z) try : Base(i,j), i(i), z(z) {
callStack.push_back("Class::Class(int, int, int)");
}
catch(const std::exception &e) {
throw e;
}
Class(Member m) : m(m) {
//this->m = m;
//BAD: m constructor would be called, but this is useless since we have already called it!
//to construct it before.
//This is an application of initialization constructors.
callStack.push_back("Class::Class(Member)");
}
/*
Copy constructor.
Classes already have this by default.
Useful to customize if class does dynamic allocation!
*/
Class(const Class& c) : i(c.i), z(c.z), m(c.m) {
callStack.push_back("Class::Class(Class)");
}
// Classes don't have constructors from base by default.
Class(const Base& b) : Base(b) {
callStack.push_back("Class::Class(Base)");
}
/*
Also calls Base destructor after
*/
~Class() { callStack.push_back("Class::~Class()"); }
// Called method overwriding.
void method() { callStack.push_back("Class::method()"); }
// OK.
template<class C=int>
void methodTemplate() {
callStack.push_back("Class::methodTemplate()");
}
// Different than overwriding non virtual methods. see polymorphism.
void virtualMethod() { callStack.push_back("Class::virtualMethod()"); }
// OK: only difference: if you have a pointer to this class,
// you can only use virtual if this is declared virtual.
//virtual void virtualMethod(){callStack.push_back("Class::virtualMethod()");}
// Definition obligatory if you want to create objects of this class.
void pureVirtual() { callStack.push_back("Class::pureVirtual()"); }
// ERROR: unlike function overloading, polyomorphism is decided at runtime
// and therefore return type must be the same as in declaration
//int pureVirtual(){return 1;}
// OK because Class is derived from Base
// called "covariant return type".
virtual Class* covariantReturn() {
callStack.push_back("Class:covariantReturn()");
return new Class;
}
// ERROR: invalid covariant
//virtual Class invalidCovariantReturn(){return Class();}
virtual void covariantArg(Class* c) {
callStack.push_back("Class:covariantArg()");
}
int i;
int z;
Member m;
Nested nested;
//Base nested class visible from here
private:
virtual void privatePureVirtual(){callStack.push_back("Class:privatePureVirtual()");};
};
//nested
// OK: you can see the nested class from derived classes
class NestedDerived : Class::Nested{};
class Class2 : public Base {
public:
Class2(){}
void pureVirtual(){callStack.push_back("Class2::pureVirtual()");}
// OK: you can override the Nested class from the Base also
class Nested{};
};
class ClassCast {
ClassCast(Class c){}
};
// ERROR:
//ClassDefault::ClassDefault(int i=0){}
/*
Illustrates the copy and swap idiom and related concepts like move contruction.
*/
class CopyAndSwap {
public:
int *is;
std::size_t n;
CopyAndSwap(std::size_t n, int val) : n(n) {
is = new int[n];
for (std::size_t i = 0; i < n; ++i) {
is[i] = val;
}
}
~CopyAndSwap(){
delete[] is;
}
CopyAndSwap& operator=(const CopyAndSwap& rhs) {
delete[] is;
is = new int[rhs.n];
return *this;
}
CopyAndSwap(const CopyAndSwap& other) {
}
};
// Design patterns
// VisibleInnerIterable
/*
this is the best way I could find to make a member
iterable object such as a container available outside
design goal:
- to change container type, you only change a single typedef
difficulty:
- there is no `Iterator` interface that iterates over anything in the stdlib
for performance reasons.
By iterable understand somtehing that has an `::iterator`,
a `begin()` and an `end()` methods, like stl containers
*/
class VisibleInnerIterable {
public:
VisibleInnerIterable();
typedef std::vector<int> Iterable;
const Iterable& getIterable();
private:
Iterable iterable;
};
VisibleInnerIterable::VisibleInnerIterable() : iterable{0,1,2} {}
const VisibleInnerIterable::Iterable& VisibleInnerIterable::getIterable() {
return iterable;
}
int main() {
#if __cplusplus >= 201103L
/*
define class inside function
*/
{
// As of C++11, classes can be defined inside functions!
// This matches the behaviour for structs in C.