move-semantics Questions
1
Why does an explicitly defaulted destructor disable default move constructor in the class? I know that it does, as explained in several existing answers. (e.g. Explicitly defaulted destructor disab...
Saraband asked 2/12, 2021 at 22:3
8
Solved
I have been looking through the Clang source code and I found this snippet:
void CompilerInstance::setInvocation(
std::shared_ptr<CompilerInvocation> Value) {
Invocation = std::move(Value...
Leroi asked 26/1, 2017 at 10:11
3
Because std::function is copyable, the standard requires that callables used to construct it also be copyable:
n337 (20.8.11.2.1)
template<class F> function(F f);
Requires: F shall be CopyCo...
Tenpenny asked 15/8, 2014 at 16:55
6
Solved
The following surely works but is very tedious:
T(const T&) = delete;
T(T&&) = delete;
T& operator=(const T&) = delete;
T& operator=(T&&) = delete;
I'm trying to ...
Ruddy asked 19/2, 2018 at 11:15
2
Solved
When a variable that is about to go out of scope is returned or thrown, its resources can be reused i.e. it can be moved from, as the following C++ program shows:
#include <iostream>
struct ...
Slide asked 8/9, 2021 at 8:24
2
Solved
I frequently need to implement C++ wrappers for "raw" resource handles, like file handles, Win32 OS handles and similar. When doing this, I also need to implement move operators, since the default ...
Granniah asked 8/10, 2019 at 4:13
1
Is there a STL container (no Boost) from which an element can removed and moved to an lvalue?
Say I have a std::vector of large objects and a variable to which I want to pop an element from the ve...
Moonset asked 14/4, 2017 at 17:13
2
Solved
Given the following code:
#include <iostream>
#include <memory>
struct A {};
struct B : public A {};
std::pair<bool, std::unique_ptr<B>> GetBoolAndB() {
return { true, s...
Kiangsu asked 13/8, 2021 at 9:8
1
According to cppreference, deriving from a non-movable class should make a derived class non-movable, too. Then why does std::is_move_constructible_v return true for the derived class?
class ...
Pinnatipartite asked 7/6, 2021 at 23:46
2
Solved
Mostly all things explained by fredoverflow(user 237K Rep.) in his Two answers
https://mcmap.net/q/15702/-what-is-move-semantics
https://mcmap.net/q/15702/-what-is-move-semantics
But while implem...
Yolandayolande asked 31/5, 2021 at 10:46
3
Solved
I've recently learned about move constructors, but a lot of the online resources don't talk about copy elision. Copy elision makes sense to me too, but it left me wondering when is the move constru...
Caput asked 1/6, 2021 at 14:48
3
Solved
From the book:
Rust won’t let us annotate a type with the Copy trait if the type, or any of its parts, has implemented the Drop trait. If the type needs something special to happen when the val...
Rossuck asked 6/8, 2018 at 9:5
1
Solved
I was told that Rust has a semantics in affine logic -- so one has deletion/weakening but not duplication/contraction.
The following compiles:
fn throw_away<A, B>(x: A, _y: B) -> A {
x
}
...
Aileneaileron asked 11/5, 2021 at 21:54
5
Here is a possible definition of std::swap:
template<class T>
void swap(T& a, T& b) {
T tmp(std::move(a));
a = std::move(b);
b = std::move(tmp);
}
I believe that
std::swap(v,v...
Olly asked 29/10, 2012 at 20:21
2
Solved
What does the C++11 standard say about self move assignment in relation to the standard library? To be more concrete, what, if anything, is guaranteed about what selfAssign does?
template<class...
Catching asked 29/10, 2012 at 18:23
2
Solved
I am trying to write a function, make_foo, that will "unwrap" a std::optional< foo >, returning the contained value.
The function assumes that the optional is engaged so does not pe...
Gildea asked 22/3, 2021 at 14:2
1
Solved
Consider this code:
#include <iostream>
template<typename A>
struct S{
S(const A& a){
std::cout << "L\n";
}
S(A&& a){
std::cout << "R\n"...
Expansile asked 19/3, 2021 at 16:37
6
Solved
If I construct a string made of a list of space separated floating point values using std::ostringstream:
std::ostringstream ss;
unsigned int s = floatData.size();
for(unsigned int i=0;i<s;i++)...
Plop asked 8/10, 2014 at 21:11
2
Solved
Move operations should be noexcept; in the first place for intuitive and reasonable semantics. The second argument is runtime performance. From the Core Guidelines, C.66, "Make move operations...
Fribble asked 3/3, 2021 at 14:35
3
Solved
I was expecting that std::make_move_iterator will always move contents, but it seems not.
It looks like it is moving elements in vector<string> but not in vector<int>.
See the below c...
Mirthamirthful asked 29/7, 2014 at 6:27
1
Solved
I recently started learning about rvalues,lvalues, move semantics and I can't understands some conceps like rvalue refs .. why can I assign a value to a rvalue ref like : int&& x = 10;.. do...
Spence asked 3/1, 2021 at 17:22
6
Solved
I am trying to understand how std::move and rvalues work in C++ 11. I keep seeing the similar example in tutorials like this:
Suppose we have this class :
class Class
{
public:
Class(Cl...
Bookseller asked 21/6, 2015 at 10:35
2
I would define "trivially movable" by
Calling the move constructor (or the move assignment operator) is
equivalent to memcpy the bytes to the new destination and not calling
the destructor on ...
Clichy asked 18/8, 2017 at 3:14
0
I am struggling to understand the different behavior shown between move and an rvalue cast
given:
template <class T> void f1(T param) { }
struct B { B() = default; B(B&&) { cout <...
Corposant asked 5/10, 2020 at 10:0
2
Solved
Given the following definitions:
object -- a contiguous region of memory holding a value of some type.
value -- the bits of an object interpreted according to the objects type.
Section 6.4.1 of t...
Vicentevicepresident asked 15/9, 2020 at 23:48
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