The class any is a type-safe container for single values of any type.
Class any is included into C++ 17 standard, see here. It is a container for single values of any type.
Functions any_cast provides access to contained object.
Questions tagged [stdany]
72 questions
0
votes
1 answer
std::any for move-only template where static_assert inside copy-ctor equals compile error, but why?
I don't see why move-only templates can not be extended by copy-ctor having a static_assert (like in the code below) in order to be used with std::any
#include
#include
namespace detail{
template
struct MoveOnly
{
…
ezegoing
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0
votes
1 answer
Reading sub-object vector with rapidjson
This is my json:
{
"data": {
"text": "hey stackoverflow",
"array_1": [
["hello", "world", 11, 14]
]
},
}
I have managed to extract the text attribute like so:
Code:
document.Parse(request_body);
auto&…
lifeguru42
- 156
- 1
- 12
0
votes
1 answer
How to expand a parameter pack into a vector
Compile problem error: no matching constructor for initialization of 'std::vector'
The code base I am building has several objects that do not need to be variadic template parameters. I wanted to make them accept a vector of std::any. My objects are…
Anthony Matarazzo
- 19
- 3
0
votes
1 answer
Cannot move std::any
The following code
using vptr = std::vector>;
auto m = std::unordered_map{};
m.try_emplace(0, move(vptr{}));
Fails to compile, complaining about using of deleted copy constructor of unique_ptr. After replacing…
Ryba
- 681
- 4
- 13
0
votes
2 answers
Storing multiple types into class member container
I was reading this Q/A here and as my question is similar but different I would like to know how to do the following:
Let's say I have a basic non template non inherited class called Storage.
class Storage {};
I would like for this class to have a…
Francis Cugler
- 7,788
- 2
- 28
- 59
0
votes
1 answer
Will it be possible to compare two arbitrary functions with std::any in C++17?
I think it is a big limitation of how C++ handles function pointers and std::function, that it is currently impossible to compare two arbitrary functions of different type in an elegant way.
I am now wondering if C++17 will change that with the…
N0vember
- 995
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- 9
- 12
-1
votes
1 answer
Transfer data from library to upper level and then back without naming it inbetween
I need to get some complex data from a library then use this data at the upper level. The data consists of 2 parts: while evaluating the data A, i get some additional data B, and the data B should be returned back in the library "as is" in order to…
tester
- 43
- 2
- 8
-1
votes
2 answers
How to correctly check any_cast available?
I have some input which can be simple value or container, packed in std::any. I don't want to use exceptions, so I call noexcept variadic any_cast method which return pointer or nullptr to value of any.
I can verify any cast available with typeid()…
Sergey Inozemcev
- 57
- 10
-1
votes
1 answer
Use std::map with std::any as value type
I'd like to have class Config able to store literally any value within a string key. For that purpose it seems that std::map fits. Unfortunately this isn't compiling.
That looks like that std::is_copy_constructible> trait…
Alexander Pushkar
- 69
- 7
-1
votes
1 answer
unordered_map with std::any values cannot any_cast string
I'm new to C++ and I was studying about std::unordered_map and std::any.
I've created a sample demo bellow which generates some dummy data and then they get inserted into the map.
After that (in the commented out code) I print out the values using…
0x_Anakin
- 3,229
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- 86
-2
votes
2 answers
How to Add Element into a std::vector using std::any
I am working on a C++17 project and there i am using std::any. A minimal reproducible example is given below for reference explaining what i want to achieve.
#include
#include
#include
int main()
{
std::vector…
user16783784
-2
votes
2 answers
Is std::any supported in MSVC 2017?
I try to compile a piece of code with:
cl /c /std:c++latest /Gm- /sdl /Zc:inline /RTC1 /Oy /MDd /FA /EHs main.cxx
but I get this error:
error C2039: 'any': is not a member of 'std'
and I wonder how (if possible) can I get to have this feature. I…
bMain
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