C++, can I overload assignment operator of a point of a class?
It is ok to overload assignment operator of a Class A, but not sure if it is allowed to overload assignment operator of pointer type of class A.
is it legitimate question or not...? If yes, how?
For example, I would like to do ref_count++ whenever we have a pointer reference on it below.
class A{
public:
A(){}
~A(){}
int ref_count{0};
}
main()
{
A* a1 = new A(); //line 1
A* a2 = a1; //line 2
}
After execution of line 1, A.ref_count is 1
After execution of line 2, A.ref_count is 2
c++ pointers operator-overloading
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
add a comment |
It is ok to overload assignment operator of a Class A, but not sure if it is allowed to overload assignment operator of pointer type of class A.
is it legitimate question or not...? If yes, how?
For example, I would like to do ref_count++ whenever we have a pointer reference on it below.
class A{
public:
A(){}
~A(){}
int ref_count{0};
}
main()
{
A* a1 = new A(); //line 1
A* a2 = a1; //line 2
}
After execution of line 1, A.ref_count is 1
After execution of line 2, A.ref_count is 2
c++ pointers operator-overloading
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
1
There is nooperator=()involved in the two lines in yourmain()
– Swordfish
Nov 13 '18 at 8:44
1
What you're doing is copy initialization, not assignment.
– Some programmer dude
Nov 13 '18 at 8:46
And no you can't overload pointer assignment. The assignment operator must be a member function, and when you assign to a pointer it will not be called.
– Some programmer dude
Nov 13 '18 at 8:47
3
Fortunately, you don't need to implement ref counting for pointers yourself, in C++ they are spelledstd::shared_ptr<A>.
– StoryTeller
Nov 13 '18 at 8:47
If you want to add more custom code other than just ref-counting, you can write your own wrapper class and overloadoperator*andoperator->for access
– dave
Nov 13 '18 at 8:49
add a comment |
It is ok to overload assignment operator of a Class A, but not sure if it is allowed to overload assignment operator of pointer type of class A.
is it legitimate question or not...? If yes, how?
For example, I would like to do ref_count++ whenever we have a pointer reference on it below.
class A{
public:
A(){}
~A(){}
int ref_count{0};
}
main()
{
A* a1 = new A(); //line 1
A* a2 = a1; //line 2
}
After execution of line 1, A.ref_count is 1
After execution of line 2, A.ref_count is 2
c++ pointers operator-overloading
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
It is ok to overload assignment operator of a Class A, but not sure if it is allowed to overload assignment operator of pointer type of class A.
is it legitimate question or not...? If yes, how?
For example, I would like to do ref_count++ whenever we have a pointer reference on it below.
class A{
public:
A(){}
~A(){}
int ref_count{0};
}
main()
{
A* a1 = new A(); //line 1
A* a2 = a1; //line 2
}
After execution of line 1, A.ref_count is 1
After execution of line 2, A.ref_count is 2
c++ pointers operator-overloading
c++ pointers operator-overloading
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
asked Nov 13 '18 at 8:42
Kelvin LaiKelvin Lai
344
344
1
There is nooperator=()involved in the two lines in yourmain()
– Swordfish
Nov 13 '18 at 8:44
1
What you're doing is copy initialization, not assignment.
– Some programmer dude
Nov 13 '18 at 8:46
And no you can't overload pointer assignment. The assignment operator must be a member function, and when you assign to a pointer it will not be called.
– Some programmer dude
Nov 13 '18 at 8:47
3
Fortunately, you don't need to implement ref counting for pointers yourself, in C++ they are spelledstd::shared_ptr<A>.
– StoryTeller
Nov 13 '18 at 8:47
If you want to add more custom code other than just ref-counting, you can write your own wrapper class and overloadoperator*andoperator->for access
– dave
Nov 13 '18 at 8:49
add a comment |
1
There is nooperator=()involved in the two lines in yourmain()
– Swordfish
Nov 13 '18 at 8:44
1
What you're doing is copy initialization, not assignment.
– Some programmer dude
Nov 13 '18 at 8:46
And no you can't overload pointer assignment. The assignment operator must be a member function, and when you assign to a pointer it will not be called.
– Some programmer dude
Nov 13 '18 at 8:47
3
Fortunately, you don't need to implement ref counting for pointers yourself, in C++ they are spelledstd::shared_ptr<A>.
– StoryTeller
Nov 13 '18 at 8:47
If you want to add more custom code other than just ref-counting, you can write your own wrapper class and overloadoperator*andoperator->for access
– dave
Nov 13 '18 at 8:49
1
1
There is no
operator=() involved in the two lines in your main()– Swordfish
Nov 13 '18 at 8:44
There is no
operator=() involved in the two lines in your main()– Swordfish
Nov 13 '18 at 8:44
1
1
What you're doing is copy initialization, not assignment.
– Some programmer dude
Nov 13 '18 at 8:46
What you're doing is copy initialization, not assignment.
– Some programmer dude
Nov 13 '18 at 8:46
And no you can't overload pointer assignment. The assignment operator must be a member function, and when you assign to a pointer it will not be called.
– Some programmer dude
Nov 13 '18 at 8:47
And no you can't overload pointer assignment. The assignment operator must be a member function, and when you assign to a pointer it will not be called.
– Some programmer dude
Nov 13 '18 at 8:47
3
3
Fortunately, you don't need to implement ref counting for pointers yourself, in C++ they are spelled
std::shared_ptr<A>.– StoryTeller
Nov 13 '18 at 8:47
Fortunately, you don't need to implement ref counting for pointers yourself, in C++ they are spelled
std::shared_ptr<A>.– StoryTeller
Nov 13 '18 at 8:47
If you want to add more custom code other than just ref-counting, you can write your own wrapper class and overload
operator* and operator-> for access– dave
Nov 13 '18 at 8:49
If you want to add more custom code other than just ref-counting, you can write your own wrapper class and overload
operator* and operator-> for access– dave
Nov 13 '18 at 8:49
add a comment |
2 Answers
2
active
oldest
votes
I believe you mean pointer assignment. Short answer: no, you can't.
answered Nov 13 '18 at 8:49
darunedarune
1,134516
add a comment |
It looks like you wan't a reference counted pointer. First lets examine why your solution doesn't work:
- Here:
A* a1 = new A();you are doing pointer assignment, not class assignment. You cannot overload this operation. - In your definition of
Class Ayou implement reference counting. This is not a good solution, what if you want a new class (Class B) that also requires reference counting? You have to implement it all over again. This is not nice or re-usable.
So, what can we do? Well, it depends on why you wan't reference counting. It seems like you wan't self managed memory. Fortunatley, c++ provides a construct for this already. It is std::shared_ptr. You can use it like this:
{
std::shared_ptr<A> a1 = std::make_shared<A>(); // Reference count is set at 1
{
std::shared_ptr<A> a2 = a1; // Reference count is incremented to 2
} // Reference count is decremented to 1
} // Reference count is decremented to 0 and the memory is released.
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
add a comment |
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2 Answers
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2 Answers
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active
oldest
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I believe you mean pointer assignment. Short answer: no, you can't.
answered Nov 13 '18 at 8:49
darunedarune
1,134516
add a comment |
I believe you mean pointer assignment. Short answer: no, you can't.
answered Nov 13 '18 at 8:49
darunedarune
1,134516
add a comment |
I believe you mean pointer assignment. Short answer: no, you can't.
answered Nov 13 '18 at 8:49
darunedarune
1,134516
I believe you mean pointer assignment. Short answer: no, you can't.
answered Nov 13 '18 at 8:49
darunedarune
1,134516
answered Nov 13 '18 at 8:49
darunedarune
1,134516
answered Nov 13 '18 at 8:49
darunedarune
1,134516
answered Nov 13 '18 at 8:49
darunedarune
1,134516
1,134516
add a comment |
add a comment |
It looks like you wan't a reference counted pointer. First lets examine why your solution doesn't work:
- Here:
A* a1 = new A();you are doing pointer assignment, not class assignment. You cannot overload this operation. - In your definition of
Class Ayou implement reference counting. This is not a good solution, what if you want a new class (Class B) that also requires reference counting? You have to implement it all over again. This is not nice or re-usable.
So, what can we do? Well, it depends on why you wan't reference counting. It seems like you wan't self managed memory. Fortunatley, c++ provides a construct for this already. It is std::shared_ptr. You can use it like this:
{
std::shared_ptr<A> a1 = std::make_shared<A>(); // Reference count is set at 1
{
std::shared_ptr<A> a2 = a1; // Reference count is incremented to 2
} // Reference count is decremented to 1
} // Reference count is decremented to 0 and the memory is released.
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
add a comment |
It looks like you wan't a reference counted pointer. First lets examine why your solution doesn't work:
- Here:
A* a1 = new A();you are doing pointer assignment, not class assignment. You cannot overload this operation. - In your definition of
Class Ayou implement reference counting. This is not a good solution, what if you want a new class (Class B) that also requires reference counting? You have to implement it all over again. This is not nice or re-usable.
So, what can we do? Well, it depends on why you wan't reference counting. It seems like you wan't self managed memory. Fortunatley, c++ provides a construct for this already. It is std::shared_ptr. You can use it like this:
{
std::shared_ptr<A> a1 = std::make_shared<A>(); // Reference count is set at 1
{
std::shared_ptr<A> a2 = a1; // Reference count is incremented to 2
} // Reference count is decremented to 1
} // Reference count is decremented to 0 and the memory is released.
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
add a comment |
It looks like you wan't a reference counted pointer. First lets examine why your solution doesn't work:
- Here:
A* a1 = new A();you are doing pointer assignment, not class assignment. You cannot overload this operation. - In your definition of
Class Ayou implement reference counting. This is not a good solution, what if you want a new class (Class B) that also requires reference counting? You have to implement it all over again. This is not nice or re-usable.
So, what can we do? Well, it depends on why you wan't reference counting. It seems like you wan't self managed memory. Fortunatley, c++ provides a construct for this already. It is std::shared_ptr. You can use it like this:
{
std::shared_ptr<A> a1 = std::make_shared<A>(); // Reference count is set at 1
{
std::shared_ptr<A> a2 = a1; // Reference count is incremented to 2
} // Reference count is decremented to 1
} // Reference count is decremented to 0 and the memory is released.
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
It looks like you wan't a reference counted pointer. First lets examine why your solution doesn't work:
- Here:
A* a1 = new A();you are doing pointer assignment, not class assignment. You cannot overload this operation. - In your definition of
Class Ayou implement reference counting. This is not a good solution, what if you want a new class (Class B) that also requires reference counting? You have to implement it all over again. This is not nice or re-usable.
So, what can we do? Well, it depends on why you wan't reference counting. It seems like you wan't self managed memory. Fortunatley, c++ provides a construct for this already. It is std::shared_ptr. You can use it like this:
{
std::shared_ptr<A> a1 = std::make_shared<A>(); // Reference count is set at 1
{
std::shared_ptr<A> a2 = a1; // Reference count is incremented to 2
} // Reference count is decremented to 1
} // Reference count is decremented to 0 and the memory is released.
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
answered Nov 13 '18 at 9:20
Fantastic Mr FoxFantastic Mr Fox
18.5k1867130
18.5k1867130
add a comment |
add a comment |
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1
There is no
operator=()involved in the two lines in yourmain()– Swordfish
Nov 13 '18 at 8:44
1
What you're doing is copy initialization, not assignment.
– Some programmer dude
Nov 13 '18 at 8:46
And no you can't overload pointer assignment. The assignment operator must be a member function, and when you assign to a pointer it will not be called.
– Some programmer dude
Nov 13 '18 at 8:47
3
Fortunately, you don't need to implement ref counting for pointers yourself, in C++ they are spelled
std::shared_ptr<A>.– StoryTeller
Nov 13 '18 at 8:47
If you want to add more custom code other than just ref-counting, you can write your own wrapper class and overload
operator*andoperator->for access– dave
Nov 13 '18 at 8:49