Object slicing refers to assignment by value of a sub-class instance to a super-class instance,thereby losing part of the information i.e. the sub-class specific data members are ignored.
Questions tagged [object-slicing]
220 questions
4
votes
2 answers
What are the undesirable results the author is talking about?
This example was taken from Bruce Eckel's "Thinking in C++" Chapter 14, Section "Upcasting and the Copy Constructor".
#include
using namespace std;
class Parent
{
int i;
public:
Parent(int ii) : i(ii) { cout << "Parent(int…
Belloc
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4
votes
3 answers
C++: Is there a more elegant solution to this (multiple dispatch) runtime polymorphism?
The main problem is simple, really. Given a base (more abstract) class and multiple derived ones that need to interact with each other, how do you go about doing it?
To give a more concrete example, here is an implementation with hitboxes for a 2d…
Andrei-Info
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- 3
4
votes
1 answer
C++ final class and slicing idiom
I happened to be browsing the source for mongoDB, and found this interesting construct:
class NonspecificAssertionException final : public AssertionException {
public:
using AssertionException::AssertionException;
private:
void…
user9987379
4
votes
2 answers
Can std::move cause slicing when moving into l-value reference?
See the following code:
#include
#include
class Parent
{
public:
Parent() = default;
virtual ~Parent() = default;
Parent(const Parent& pr) : i{pr.i} {std::cout << "Parent copy constructor\n";}
Parent&…
ToddR
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4
votes
1 answer
How to prevent move slicing?
When a derived class instance is passed as a r-value parent reference to an unsuspecting method, the latter can legally change the parent's contents, causing incoherence with any extra data stored in the actual object. Therefore a class designed for…
The Vee
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4
votes
1 answer
Polymorphism: member acces and getter give different results
Here is the code:
#include
#include
#include
class Parent
{
public:
virtual void whatAmI(){std::cout << "A Parent" << std::endl;}
virtual long getValue(){std::cout << "value from Parent " << std::endl; return…
Rrr
- 53
- 4
4
votes
3 answers
Does std::move result in slicing?
For example, in
unique_ptr = new deriv;
std::vector>.push_back(std::move(deriv));
will deriv be sliced to type unique_ptr
user383352
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4
votes
2 answers
Slicing in C++ where I am wrong?
I read about the slicing problem in C++ and I tried some examples (I am from Java background). Unfortunatelly, I do not understand some of the behaviour. Currently, I am stucked in this example (alternated example from Efficent C++ Third Edition).…
napets
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4
votes
2 answers
Preventing slicing in copy constructor
I want to copy a vector of type Foo objects but the objects can be several different derived types of Foo. I can't figure out how to copy without slicing. Here's my toy code
#include "stdafx.h"
#include
#include
#include…
Phlox Midas
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3
votes
3 answers
Are subclasses that only change the members valid practice?
Lets say I have a class A that has a member of type int.
I have a class B which is a subclass of A.
B is meant to initialize the members to some state and has no other purpose.
#include
#include
struct A {
int someInt;
…
Raildex
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3
votes
5 answers
Smart Pointers In C++
Say we have a base class and a derived. So:
class base {
protected:
~base(){
//...
}
// ...
};
class derived : public base {
// ...
};
And now say that we have this code using the above classes…
K-RAN
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3
votes
2 answers
C++: object slicing and exceptions
In an interview I was asked why catching exceptions by value can be a problem and I answered that this can cause object slicing. And this is what I find in the Internet, for example here: https://www.viva64.com/en/w/v746/
But now I am trying to…
Andrey Rubliov
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3
votes
2 answers
c++ prevent object slicing in std::vector
I would like to store multiple classes with the same base class in a std::vector. After some research, it became apparent to me that I have to use pointers to prevent object slicing. However, when I create the vector, add elements to it and return…
Rheel
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3
votes
8 answers
How do I store different classes in a single vector?
So I have a vector full of all the objects for my game; things like the player object, enemy object, walls, etc... All things in the vector are children of Framework, so I made the vector type Framework because that was the closest thing to a…
null
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3
votes
2 answers
c++ polymorphism, name resolution for derived class
class Base {
public:
virtual void f(float) { cout << "Base::f(float)\n"; }
};
class Derived : public Base {
public:
virtual void f(int) { cout << "Derived::f(int)\n"; }
};
int main() {
Derived *d = new Derived();
Base *b =…
legokangpalla
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