Threading and Polymorphism
-2
#include<iostream>
#include <thread>
#include <algorithm>
#include <vector>
#include <functional>
using namespace std;
class base
{
public:
virtual void fun_1() { cout << "base-1n"; }
virtual void fun_2() { cout << "base-2n"; }
};
class derived : public base
{
public:
void fun_1() { cout << "derived-1n"; }
void fun_2() { cout << "derived-2n";
}
};
class caller
{
private:
base *p;
derived obj1;
p = &obj1;
public:
void me()
{
std::thread t(std::bind(&base::fun_2, p), this);
t.join();
}
};
int main()
{
caller c;
c.me();
return 0;
}
I have a written a very simple threading and polymorphism example. All I wanted to do is to call a derived function from a different class which is containing that another class object. The program fails to compile with the message p does not name a type which I could not understand why.
c++
edited Nov 22 '18 at 16:24
payo
3,64511529
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
|
show 1 more comment
-2
#include<iostream>
#include <thread>
#include <algorithm>
#include <vector>
#include <functional>
using namespace std;
class base
{
public:
virtual void fun_1() { cout << "base-1n"; }
virtual void fun_2() { cout << "base-2n"; }
};
class derived : public base
{
public:
void fun_1() { cout << "derived-1n"; }
void fun_2() { cout << "derived-2n";
}
};
class caller
{
private:
base *p;
derived obj1;
p = &obj1;
public:
void me()
{
std::thread t(std::bind(&base::fun_2, p), this);
t.join();
}
};
int main()
{
caller c;
c.me();
return 0;
}
I have a written a very simple threading and polymorphism example. All I wanted to do is to call a derived function from a different class which is containing that another class object. The program fails to compile with the message p does not name a type which I could not understand why.
c++
edited Nov 22 '18 at 16:24
payo
3,64511529
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
5
p = &obj1doesn't make sense in the body of the class definition. It's a statement, and must be within some function, sayme.
– Igor Tandetnik
Nov 22 '18 at 14:15
3
You can't have generic statements in the declaration section of a class, all statements must be inside functions. I also think you should read more about constructor initializer lists as a way to initialize members (likep).
– Some programmer dude
Nov 22 '18 at 14:15
1
You don't needp, you can pass&obj1tobind.
– molbdnilo
Nov 22 '18 at 14:29
Just a suggestion: you don't needcallerif all you want to do is explore polymorphism and threads. Inmain:derived obj1; base *p = &obj1; std::thread t(&base::fun_2, p); t.join();. The constructor forstd::threaddoes just about everything thatstd::binddoes.
– Pete Becker
Nov 22 '18 at 14:37
this question has nothing to do with threads
– payo
Nov 22 '18 at 16:24
|
show 1 more comment
-2
-2
-2
#include<iostream>
#include <thread>
#include <algorithm>
#include <vector>
#include <functional>
using namespace std;
class base
{
public:
virtual void fun_1() { cout << "base-1n"; }
virtual void fun_2() { cout << "base-2n"; }
};
class derived : public base
{
public:
void fun_1() { cout << "derived-1n"; }
void fun_2() { cout << "derived-2n";
}
};
class caller
{
private:
base *p;
derived obj1;
p = &obj1;
public:
void me()
{
std::thread t(std::bind(&base::fun_2, p), this);
t.join();
}
};
int main()
{
caller c;
c.me();
return 0;
}
I have a written a very simple threading and polymorphism example. All I wanted to do is to call a derived function from a different class which is containing that another class object. The program fails to compile with the message p does not name a type which I could not understand why.
c++
edited Nov 22 '18 at 16:24
payo
3,64511529
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
#include<iostream>
#include <thread>
#include <algorithm>
#include <vector>
#include <functional>
using namespace std;
class base
{
public:
virtual void fun_1() { cout << "base-1n"; }
virtual void fun_2() { cout << "base-2n"; }
};
class derived : public base
{
public:
void fun_1() { cout << "derived-1n"; }
void fun_2() { cout << "derived-2n";
}
};
class caller
{
private:
base *p;
derived obj1;
p = &obj1;
public:
void me()
{
std::thread t(std::bind(&base::fun_2, p), this);
t.join();
}
};
int main()
{
caller c;
c.me();
return 0;
}
I have a written a very simple threading and polymorphism example. All I wanted to do is to call a derived function from a different class which is containing that another class object. The program fails to compile with the message p does not name a type which I could not understand why.
c++
c++
edited Nov 22 '18 at 16:24
payo
3,64511529
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
edited Nov 22 '18 at 16:24
payo
3,64511529
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
edited Nov 22 '18 at 16:24
payo
3,64511529
edited Nov 22 '18 at 16:24
payo
3,64511529
edited Nov 22 '18 at 16:24
payo
3,64511529
3,64511529
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
asked Nov 22 '18 at 14:13
Roshan MehtaRoshan Mehta
85211032
85211032
5
p = &obj1doesn't make sense in the body of the class definition. It's a statement, and must be within some function, sayme.
– Igor Tandetnik
Nov 22 '18 at 14:15
3
You can't have generic statements in the declaration section of a class, all statements must be inside functions. I also think you should read more about constructor initializer lists as a way to initialize members (likep).
– Some programmer dude
Nov 22 '18 at 14:15
1
You don't needp, you can pass&obj1tobind.
– molbdnilo
Nov 22 '18 at 14:29
Just a suggestion: you don't needcallerif all you want to do is explore polymorphism and threads. Inmain:derived obj1; base *p = &obj1; std::thread t(&base::fun_2, p); t.join();. The constructor forstd::threaddoes just about everything thatstd::binddoes.
– Pete Becker
Nov 22 '18 at 14:37
this question has nothing to do with threads
– payo
Nov 22 '18 at 16:24
|
show 1 more comment
5
p = &obj1doesn't make sense in the body of the class definition. It's a statement, and must be within some function, sayme.
– Igor Tandetnik
Nov 22 '18 at 14:15
3
You can't have generic statements in the declaration section of a class, all statements must be inside functions. I also think you should read more about constructor initializer lists as a way to initialize members (likep).
– Some programmer dude
Nov 22 '18 at 14:15
1
You don't needp, you can pass&obj1tobind.
– molbdnilo
Nov 22 '18 at 14:29
Just a suggestion: you don't needcallerif all you want to do is explore polymorphism and threads. Inmain:derived obj1; base *p = &obj1; std::thread t(&base::fun_2, p); t.join();. The constructor forstd::threaddoes just about everything thatstd::binddoes.
– Pete Becker
Nov 22 '18 at 14:37
this question has nothing to do with threads
– payo
Nov 22 '18 at 16:24
5
5
p = &obj1 doesn't make sense in the body of the class definition. It's a statement, and must be within some function, say me.– Igor Tandetnik
Nov 22 '18 at 14:15
p = &obj1 doesn't make sense in the body of the class definition. It's a statement, and must be within some function, say me.– Igor Tandetnik
Nov 22 '18 at 14:15
3
3
You can't have generic statements in the declaration section of a class, all statements must be inside functions. I also think you should read more about constructor initializer lists as a way to initialize members (like
p).– Some programmer dude
Nov 22 '18 at 14:15
You can't have generic statements in the declaration section of a class, all statements must be inside functions. I also think you should read more about constructor initializer lists as a way to initialize members (like
p).– Some programmer dude
Nov 22 '18 at 14:15
1
1
You don't need
p, you can pass &obj1 to bind.– molbdnilo
Nov 22 '18 at 14:29
You don't need
p, you can pass &obj1 to bind.– molbdnilo
Nov 22 '18 at 14:29
Just a suggestion: you don't need
caller if all you want to do is explore polymorphism and threads. In main: derived obj1; base *p = &obj1; std::thread t(&base::fun_2, p); t.join();. The constructor for std::thread does just about everything that std::bind does.– Pete Becker
Nov 22 '18 at 14:37
Just a suggestion: you don't need
caller if all you want to do is explore polymorphism and threads. In main: derived obj1; base *p = &obj1; std::thread t(&base::fun_2, p); t.join();. The constructor for std::thread does just about everything that std::bind does.– Pete Becker
Nov 22 '18 at 14:37
this question has nothing to do with threads
– payo
Nov 22 '18 at 16:24
this question has nothing to do with threads
– payo
Nov 22 '18 at 16:24
|
show 1 more comment
1 Answer
1
active
oldest
votes
1
Your error is in line:
p = &obj1;
It is better to write like this, it should help:
class caller
{
private:
derived obj1;
base *p = &obj1;
......
};
or initialize pointer in costructor:
class caller
{
private:
derived obj1;
base *p = nullptr;
caller() : p(&obj1) {}
......
};
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
add a comment |
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1 Answer
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1 Answer
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active
oldest
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oldest
votes
1
Your error is in line:
p = &obj1;
It is better to write like this, it should help:
class caller
{
private:
derived obj1;
base *p = &obj1;
......
};
or initialize pointer in costructor:
class caller
{
private:
derived obj1;
base *p = nullptr;
caller() : p(&obj1) {}
......
};
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
add a comment |
1
Your error is in line:
p = &obj1;
It is better to write like this, it should help:
class caller
{
private:
derived obj1;
base *p = &obj1;
......
};
or initialize pointer in costructor:
class caller
{
private:
derived obj1;
base *p = nullptr;
caller() : p(&obj1) {}
......
};
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
add a comment |
1
1
1
Your error is in line:
p = &obj1;
It is better to write like this, it should help:
class caller
{
private:
derived obj1;
base *p = &obj1;
......
};
or initialize pointer in costructor:
class caller
{
private:
derived obj1;
base *p = nullptr;
caller() : p(&obj1) {}
......
};
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
Your error is in line:
p = &obj1;
It is better to write like this, it should help:
class caller
{
private:
derived obj1;
base *p = &obj1;
......
};
or initialize pointer in costructor:
class caller
{
private:
derived obj1;
base *p = nullptr;
caller() : p(&obj1) {}
......
};
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
edited Nov 22 '18 at 14:30
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
answered Nov 22 '18 at 14:19
snake_stylesnake_style
1,170410
1,170410
add a comment |
add a comment |
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5
p = &obj1doesn't make sense in the body of the class definition. It's a statement, and must be within some function, sayme.– Igor Tandetnik
Nov 22 '18 at 14:15
3
You can't have generic statements in the declaration section of a class, all statements must be inside functions. I also think you should read more about constructor initializer lists as a way to initialize members (like
p).– Some programmer dude
Nov 22 '18 at 14:15
1
You don't need
p, you can pass&obj1tobind.– molbdnilo
Nov 22 '18 at 14:29
Just a suggestion: you don't need
callerif all you want to do is explore polymorphism and threads. Inmain:derived obj1; base *p = &obj1; std::thread t(&base::fun_2, p); t.join();. The constructor forstd::threaddoes just about everything thatstd::binddoes.– Pete Becker
Nov 22 '18 at 14:37
this question has nothing to do with threads
– payo
Nov 22 '18 at 16:24