Polymorphic list and pointers
I am new to C++ and am struggling on polymorphism.
I have a project where I need to have a base class (let's say Master) and three derived class.
class Master {
public :
virtual void run();
//Other attributes non-important for the topic
}
class Derived1 : public Master {
public:
void run();
//attributes
}
class Derived2 : public Master{
public :
Derived2(Derived1* ptr1) {ptr = ptr1;} //there comes the cause of the problem
void run();
private :
Derived1* ptr;
}
In my main I want to create a polymorphic list vector<Master*> poly_list;
But the problem is that this list only contains pointers on the Master class so even if it could call the right function run(); I cannot send the address of Derived1 to the constructor of Derived2.
I wanted to proceed like this :
int main
{
vector<Master*> poly_list;
poly_list.push_back(new Derived1());
poly_list.push_back(new Derived2(poly_list[0]));
return 0
}
And when I compile the code the compiler tells me that it cannot convert type Master to Derived1 for the constructor.
Anybody has a way for this to work ? Thanks by advance.
polymorphism
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
add a comment |
I am new to C++ and am struggling on polymorphism.
I have a project where I need to have a base class (let's say Master) and three derived class.
class Master {
public :
virtual void run();
//Other attributes non-important for the topic
}
class Derived1 : public Master {
public:
void run();
//attributes
}
class Derived2 : public Master{
public :
Derived2(Derived1* ptr1) {ptr = ptr1;} //there comes the cause of the problem
void run();
private :
Derived1* ptr;
}
In my main I want to create a polymorphic list vector<Master*> poly_list;
But the problem is that this list only contains pointers on the Master class so even if it could call the right function run(); I cannot send the address of Derived1 to the constructor of Derived2.
I wanted to proceed like this :
int main
{
vector<Master*> poly_list;
poly_list.push_back(new Derived1());
poly_list.push_back(new Derived2(poly_list[0]));
return 0
}
And when I compile the code the compiler tells me that it cannot convert type Master to Derived1 for the constructor.
Anybody has a way for this to work ? Thanks by advance.
polymorphism
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
add a comment |
I am new to C++ and am struggling on polymorphism.
I have a project where I need to have a base class (let's say Master) and three derived class.
class Master {
public :
virtual void run();
//Other attributes non-important for the topic
}
class Derived1 : public Master {
public:
void run();
//attributes
}
class Derived2 : public Master{
public :
Derived2(Derived1* ptr1) {ptr = ptr1;} //there comes the cause of the problem
void run();
private :
Derived1* ptr;
}
In my main I want to create a polymorphic list vector<Master*> poly_list;
But the problem is that this list only contains pointers on the Master class so even if it could call the right function run(); I cannot send the address of Derived1 to the constructor of Derived2.
I wanted to proceed like this :
int main
{
vector<Master*> poly_list;
poly_list.push_back(new Derived1());
poly_list.push_back(new Derived2(poly_list[0]));
return 0
}
And when I compile the code the compiler tells me that it cannot convert type Master to Derived1 for the constructor.
Anybody has a way for this to work ? Thanks by advance.
polymorphism
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
I am new to C++ and am struggling on polymorphism.
I have a project where I need to have a base class (let's say Master) and three derived class.
class Master {
public :
virtual void run();
//Other attributes non-important for the topic
}
class Derived1 : public Master {
public:
void run();
//attributes
}
class Derived2 : public Master{
public :
Derived2(Derived1* ptr1) {ptr = ptr1;} //there comes the cause of the problem
void run();
private :
Derived1* ptr;
}
In my main I want to create a polymorphic list vector<Master*> poly_list;
But the problem is that this list only contains pointers on the Master class so even if it could call the right function run(); I cannot send the address of Derived1 to the constructor of Derived2.
I wanted to proceed like this :
int main
{
vector<Master*> poly_list;
poly_list.push_back(new Derived1());
poly_list.push_back(new Derived2(poly_list[0]));
return 0
}
And when I compile the code the compiler tells me that it cannot convert type Master to Derived1 for the constructor.
Anybody has a way for this to work ? Thanks by advance.
polymorphism
polymorphism
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
asked Nov 17 '18 at 13:20
Ulysse Touchais
84
84
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
Yes, take a pointer of Derived1 before pushing it into the list:
vector<Master*> poly_list;
Derived1 *d=new Derived1();
poly_list.push_back(d);
poly_list.push_back(new Derived2(d));
Also, please, instead of using raw pointers, please, use std::unique_ptr smart pointer, so you will not leak memory if forgetting of doing delete, just as you are doing in your example.
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, take a pointer of Derived1 before pushing it into the list:
vector<Master*> poly_list;
Derived1 *d=new Derived1();
poly_list.push_back(d);
poly_list.push_back(new Derived2(d));
Also, please, instead of using raw pointers, please, use std::unique_ptr smart pointer, so you will not leak memory if forgetting of doing delete, just as you are doing in your example.
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
add a comment |
Yes, take a pointer of Derived1 before pushing it into the list:
vector<Master*> poly_list;
Derived1 *d=new Derived1();
poly_list.push_back(d);
poly_list.push_back(new Derived2(d));
Also, please, instead of using raw pointers, please, use std::unique_ptr smart pointer, so you will not leak memory if forgetting of doing delete, just as you are doing in your example.
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
add a comment |
Yes, take a pointer of Derived1 before pushing it into the list:
vector<Master*> poly_list;
Derived1 *d=new Derived1();
poly_list.push_back(d);
poly_list.push_back(new Derived2(d));
Also, please, instead of using raw pointers, please, use std::unique_ptr smart pointer, so you will not leak memory if forgetting of doing delete, just as you are doing in your example.
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
Yes, take a pointer of Derived1 before pushing it into the list:
vector<Master*> poly_list;
Derived1 *d=new Derived1();
poly_list.push_back(d);
poly_list.push_back(new Derived2(d));
Also, please, instead of using raw pointers, please, use std::unique_ptr smart pointer, so you will not leak memory if forgetting of doing delete, just as you are doing in your example.
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
answered Nov 17 '18 at 15:14
LoPiTaL
1,566914
1,566914
add a comment |
add a comment |
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