C++ Using Setter of a member object
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I'm currently working on my first project using classes and objects, and I've run into a bit of a roadblock with my setter. I made up an example to illustrate the issue I'm running into (all one file for the sake of simplicity).
#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;
class Example1
{
public:
Example1() { name = "Mike"; }
Example1(string aName) { name = aName; }
string GetName() const { return name; }
void SetName(string newName) { name = newName; }
private:
string name;
};
class Example2
{
public:
Example2() : anObj() {}
Example2(string aName) : anObj(aName) {}
Example1 GetObj() const { return anObj; }
void SetObj(string objName) { anObj.SetName(objName); }
private:
Example1 anObj;
};
int main()
{
Example2 myObj;
cout << myObj.GetObj().GetName() << endl;
myObj.GetObj().SetName("Stan");
cout << myObj.GetObj().GetName() << endl;
}
Output:
Mike
Mike
The idea is to alter the member object in Example2 by using the member object's setter method, but the setter method doesn't seem to be working the way I expected.
I tried accessing the member by moving it to public (in Example2) and using dot notation, and that successfully changed the name. I'm not sure what the differentiation is, but, since the getter is working properly, I feel like something is wrong with how I'm using the setter.
The original problem I was trying to solve was having a Game class with a Player class member object. The idea is that the player could change their name if they wanted to.
Appreciate any help. Thanks.
c++ class setter
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
|
show 2 more comments
I'm currently working on my first project using classes and objects, and I've run into a bit of a roadblock with my setter. I made up an example to illustrate the issue I'm running into (all one file for the sake of simplicity).
#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;
class Example1
{
public:
Example1() { name = "Mike"; }
Example1(string aName) { name = aName; }
string GetName() const { return name; }
void SetName(string newName) { name = newName; }
private:
string name;
};
class Example2
{
public:
Example2() : anObj() {}
Example2(string aName) : anObj(aName) {}
Example1 GetObj() const { return anObj; }
void SetObj(string objName) { anObj.SetName(objName); }
private:
Example1 anObj;
};
int main()
{
Example2 myObj;
cout << myObj.GetObj().GetName() << endl;
myObj.GetObj().SetName("Stan");
cout << myObj.GetObj().GetName() << endl;
}
Output:
Mike
Mike
The idea is to alter the member object in Example2 by using the member object's setter method, but the setter method doesn't seem to be working the way I expected.
I tried accessing the member by moving it to public (in Example2) and using dot notation, and that successfully changed the name. I'm not sure what the differentiation is, but, since the getter is working properly, I feel like something is wrong with how I'm using the setter.
The original problem I was trying to solve was having a Game class with a Player class member object. The idea is that the player could change their name if they wanted to.
Appreciate any help. Thanks.
c++ class setter
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
Grab your C++ book of choice and read the chapter about "return by reference" / "return by value".
– zett42
Nov 24 '18 at 0:11
Handy reading: What's the difference between passing by reference vs. passing by value?
– user4581301
Nov 24 '18 at 0:12
See how much easier your code is to read with 3 minutes of formatting?
– Lightness Races in Orbit
Nov 24 '18 at 0:17
Why do you use the initialization-list forExample2::anObjbut not forExample1::name?
– Swordfish
Nov 24 '18 at 0:17
@LightnessRacesinOrbit it was 4.2 minutes.
– Swordfish
Nov 24 '18 at 0:17
|
show 2 more comments
I'm currently working on my first project using classes and objects, and I've run into a bit of a roadblock with my setter. I made up an example to illustrate the issue I'm running into (all one file for the sake of simplicity).
#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;
class Example1
{
public:
Example1() { name = "Mike"; }
Example1(string aName) { name = aName; }
string GetName() const { return name; }
void SetName(string newName) { name = newName; }
private:
string name;
};
class Example2
{
public:
Example2() : anObj() {}
Example2(string aName) : anObj(aName) {}
Example1 GetObj() const { return anObj; }
void SetObj(string objName) { anObj.SetName(objName); }
private:
Example1 anObj;
};
int main()
{
Example2 myObj;
cout << myObj.GetObj().GetName() << endl;
myObj.GetObj().SetName("Stan");
cout << myObj.GetObj().GetName() << endl;
}
Output:
Mike
Mike
The idea is to alter the member object in Example2 by using the member object's setter method, but the setter method doesn't seem to be working the way I expected.
I tried accessing the member by moving it to public (in Example2) and using dot notation, and that successfully changed the name. I'm not sure what the differentiation is, but, since the getter is working properly, I feel like something is wrong with how I'm using the setter.
The original problem I was trying to solve was having a Game class with a Player class member object. The idea is that the player could change their name if they wanted to.
Appreciate any help. Thanks.
c++ class setter
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
I'm currently working on my first project using classes and objects, and I've run into a bit of a roadblock with my setter. I made up an example to illustrate the issue I'm running into (all one file for the sake of simplicity).
#include <stdio.h>
#include <iostream>
#include <string>
using namespace std;
class Example1
{
public:
Example1() { name = "Mike"; }
Example1(string aName) { name = aName; }
string GetName() const { return name; }
void SetName(string newName) { name = newName; }
private:
string name;
};
class Example2
{
public:
Example2() : anObj() {}
Example2(string aName) : anObj(aName) {}
Example1 GetObj() const { return anObj; }
void SetObj(string objName) { anObj.SetName(objName); }
private:
Example1 anObj;
};
int main()
{
Example2 myObj;
cout << myObj.GetObj().GetName() << endl;
myObj.GetObj().SetName("Stan");
cout << myObj.GetObj().GetName() << endl;
}
Output:
Mike
Mike
The idea is to alter the member object in Example2 by using the member object's setter method, but the setter method doesn't seem to be working the way I expected.
I tried accessing the member by moving it to public (in Example2) and using dot notation, and that successfully changed the name. I'm not sure what the differentiation is, but, since the getter is working properly, I feel like something is wrong with how I'm using the setter.
The original problem I was trying to solve was having a Game class with a Player class member object. The idea is that the player could change their name if they wanted to.
Appreciate any help. Thanks.
c++ class setter
c++ class setter
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
edited Nov 24 '18 at 0:16
Swordfish
10.2k11437
10.2k11437
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
asked Nov 24 '18 at 0:03
Mike SchultzMike Schultz
112
112
Grab your C++ book of choice and read the chapter about "return by reference" / "return by value".
– zett42
Nov 24 '18 at 0:11
Handy reading: What's the difference between passing by reference vs. passing by value?
– user4581301
Nov 24 '18 at 0:12
See how much easier your code is to read with 3 minutes of formatting?
– Lightness Races in Orbit
Nov 24 '18 at 0:17
Why do you use the initialization-list forExample2::anObjbut not forExample1::name?
– Swordfish
Nov 24 '18 at 0:17
@LightnessRacesinOrbit it was 4.2 minutes.
– Swordfish
Nov 24 '18 at 0:17
|
show 2 more comments
Grab your C++ book of choice and read the chapter about "return by reference" / "return by value".
– zett42
Nov 24 '18 at 0:11
Handy reading: What's the difference between passing by reference vs. passing by value?
– user4581301
Nov 24 '18 at 0:12
See how much easier your code is to read with 3 minutes of formatting?
– Lightness Races in Orbit
Nov 24 '18 at 0:17
Why do you use the initialization-list forExample2::anObjbut not forExample1::name?
– Swordfish
Nov 24 '18 at 0:17
@LightnessRacesinOrbit it was 4.2 minutes.
– Swordfish
Nov 24 '18 at 0:17
Grab your C++ book of choice and read the chapter about "return by reference" / "return by value".
– zett42
Nov 24 '18 at 0:11
Grab your C++ book of choice and read the chapter about "return by reference" / "return by value".
– zett42
Nov 24 '18 at 0:11
Handy reading: What's the difference between passing by reference vs. passing by value?
– user4581301
Nov 24 '18 at 0:12
Handy reading: What's the difference between passing by reference vs. passing by value?
– user4581301
Nov 24 '18 at 0:12
See how much easier your code is to read with 3 minutes of formatting?
– Lightness Races in Orbit
Nov 24 '18 at 0:17
See how much easier your code is to read with 3 minutes of formatting?
– Lightness Races in Orbit
Nov 24 '18 at 0:17
Why do you use the initialization-list for
Example2::anObj but not for Example1::name?– Swordfish
Nov 24 '18 at 0:17
Why do you use the initialization-list for
Example2::anObj but not for Example1::name?– Swordfish
Nov 24 '18 at 0:17
@LightnessRacesinOrbit it was 4.2 minutes.
– Swordfish
Nov 24 '18 at 0:17
@LightnessRacesinOrbit it was 4.2 minutes.
– Swordfish
Nov 24 '18 at 0:17
|
show 2 more comments
1 Answer
1
active
oldest
votes
All your getters return a new object. Don't. Let them return a const &. But then you need a non const getter when you modify objects to call the setters:
const Example1& GetObj() const;
Example1& GetObj();
And now, the objects that are stored underneath will be updated, and not just their copies. Same for the strings.
You can also see the fact that the setters are not working on the proper objects by using a debugger.
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
add a comment |
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1 Answer
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votes
All your getters return a new object. Don't. Let them return a const &. But then you need a non const getter when you modify objects to call the setters:
const Example1& GetObj() const;
Example1& GetObj();
And now, the objects that are stored underneath will be updated, and not just their copies. Same for the strings.
You can also see the fact that the setters are not working on the proper objects by using a debugger.
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
add a comment |
All your getters return a new object. Don't. Let them return a const &. But then you need a non const getter when you modify objects to call the setters:
const Example1& GetObj() const;
Example1& GetObj();
And now, the objects that are stored underneath will be updated, and not just their copies. Same for the strings.
You can also see the fact that the setters are not working on the proper objects by using a debugger.
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
add a comment |
All your getters return a new object. Don't. Let them return a const &. But then you need a non const getter when you modify objects to call the setters:
const Example1& GetObj() const;
Example1& GetObj();
And now, the objects that are stored underneath will be updated, and not just their copies. Same for the strings.
You can also see the fact that the setters are not working on the proper objects by using a debugger.
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
All your getters return a new object. Don't. Let them return a const &. But then you need a non const getter when you modify objects to call the setters:
const Example1& GetObj() const;
Example1& GetObj();
And now, the objects that are stored underneath will be updated, and not just their copies. Same for the strings.
You can also see the fact that the setters are not working on the proper objects by using a debugger.
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
answered Nov 24 '18 at 0:06
Matthieu BrucherMatthieu Brucher
17.7k52445
17.7k52445
add a comment |
add a comment |
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Grab your C++ book of choice and read the chapter about "return by reference" / "return by value".
– zett42
Nov 24 '18 at 0:11
Handy reading: What's the difference between passing by reference vs. passing by value?
– user4581301
Nov 24 '18 at 0:12
See how much easier your code is to read with 3 minutes of formatting?
– Lightness Races in Orbit
Nov 24 '18 at 0:17
Why do you use the initialization-list for
Example2::anObjbut not forExample1::name?– Swordfish
Nov 24 '18 at 0:17
@LightnessRacesinOrbit it was 4.2 minutes.
– Swordfish
Nov 24 '18 at 0:17