Questions tagged [reference-wrapper]
107 questions
0
votes
1 answer
Transform vector of reference wrapper to Base class to vector of reference_wrapper to Derived class cannot dynamic cast
As in title. I got this error when trying to dynamic_cast
cannot dynamic_cast '(&
obj)->std::reference_wrapper<_Tp>::get()' (of type 'class
MEPObject') to type 'class MEPGene&' (target is not pointer or
reference to complete type)
…
user3191398
0
votes
1 answer
Transform std:vector> to std:vector> Runtime error time: 0 memory: 3412 signal:6
I am trying to convert vector of references to Base objects to vector of references to Derived objects. Everything is compiling fine, but i got this error: Runtime error time: 0 memory: 3412 signal:6
This is my code:
#include
#include…
user3191398
0
votes
0 answers
Is this a good use of reference_wrapper?
From what I understand, the C++ template class reference_wrapper is useful for references in containers and tuples, because it essentially provides a copy-constructor and assignment operator to normal references. In other words, it seems to be like…
Caetano Sauer
- 263
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0
votes
1 answer
Polymorphism in C++ with a vector with base classes and reference_wrapper
I need to use polymorphism in C++ for objects which are stored in a vector.
Understand from other questions that the objects in the vector need to be stored by reference since otherwise object slicing occurs.
My understanding is that…
dparnas
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0
votes
1 answer
How should I convert a container to a container of reference_wrappers?
Question:
Assume a function
void doFoo(const std::vector >& data);
where DataT is some type holding some data. I used std::vector just as the typical example of a container class.
What would you say is the most elegant…
user2296653
- 1,151
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0
votes
1 answer
Where's my bad_alloc coming from?
I have this code. scores is a field in HiscoreTable of type std::vector>
void HiscoreTable::replaceRecord(Record rec)
{
bool found = false;
for (reference_wrapper r : scores) {
if (r.get().name == rec.name)…
Matt G
- 1,661
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0
votes
2 answers
Cast pointer to reference_wrapper to pointer to underlying?
Here's my situation:
I'm given data as a pointer say double*.
I want to wrap this in a vector to use a library, and to avoid messing around with pointers.
Not wanting to copy the entire array, I use a vector of reference wrappers. If I then want to…
retrocookie
- 319
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- 10
0
votes
5 answers
reference_wrapper Referencing Primitive
I was under the impression that I could use reference_wrapper to generate a functor that would return the object passed into the reference_wrapper ctor. But this isn't working. Am I doing it wrong? If so is there a better way to accomplish this? I…
Jonathan Mee
- 37,899
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0
votes
0 answers
Semantics for wrapped objects: reference/value by default via std::move/std::ref
In recent times I am using often a natural idiom I "discovered" in C++11 that is that wrapped object can automatically hold reference when this is possible. The main question here will be about the comparison with the behavior of this "idiom" to…
alfC
- 14,261
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-1
votes
1 answer
What is the correct way to pass a std::vector to be a parameter?
I want to pass the a vector filled with object based same class.
Both std::reference_wrapper and no-reference do not fix it.
What's the correct way to solve this?
class MyClass
{
public:
MyClass(int){};
virtual void print() const {
…
Ringo_D
- 784
- 5
- 18
-1
votes
1 answer
Return C++ reference wrapper
Is it dangerous to return a reference wrapper like showed below:
std::vector> foo() {
int x = 10;
std::vector> vec;
vec.push_back(x);
return vec;
}
foo2() {
std::cout <<…
user1056903
- 921
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- 26
-1
votes
2 answers
Change of address after re-allocation
In the code below, whenever a new member is inserted to the std::vectorA, due to memory re-allocations, std::vector>B points to a wrong address. Is it possible to make the referencing vector to track the re-allocations…
Shibli
- 5,879
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- 126
-1
votes
2 answers
Is there anything like a std::value_wrapper parallel to std::reference_wrapper?
(UPDATE: This question stems from an implementation of a wrapper class passed by value for an object that has different meanings for const Foo and Foo, a move based entirely on strong opinions from people here. Prior, I'd been passing around const…
HostileFork says dont trust SE
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-2
votes
1 answer
std::function from std::bind initialization in the initializer list
I have a map of actions to be taken upon certain choice,
struct option {
int num;
std::string txt;
std::function action;
};
void funct_with_params(int &a, int &b)
{
a = 3; b = 4;
}
int param1 = 1;
int param2 = 3;
I want to…
cerkiewny
- 2,761
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-2
votes
1 answer
reference_wrapper implementation details
How does this templated operator() work in reference_wrapper implementation
template
class reference_wrapper {
public:
// types
typedef T type;
// construct/copy/destroy
reference_wrapper(T& ref) noexcept :…
barney
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