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
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Is it possible to store and retrieve a container (e.g. std::vector) in an std::any variable?
I would like to have heterogenous map in C++ for my unit test values.
Other threads recommended the use of std::any with any_cast for this purpose.
This works well for primitive types like int and double but I fail to retrieve the value if I use a…
Dennix
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Is there a way to access the internal pointer of std::any using std::any_cast?
I can't get std::any running properly in the following peace of code. What I'd like to achieve is to return a reference/ pointer to the object hold by std::any. The version below using a void pointer is just running fine.
How can I translate that…
andir
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Why does std::function::operator= in C++ always construct and not assign object?
This query is mainly based on std::function::operator= and std::any::operator=. The documentation shows that they are always implemented by constructing a new temporary object and swapping it with this object using the swap function,…
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Creating a vector of the type of std::any
Consider the following example
#include
#include
#include
#include
Atharva Dubey
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Does C++ standard guarantee such kinds of indirect access well defined?
Below has 3 different styles for indirect accessing. I am trying to understand if they all have well-defined behavior, and can be safely used for cross-platform code.
#include
#include
#include
using namespace std;
#if…
Home of the Brave
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C++ std::any how to check if type of std::any is vector
#include
#include
#include
#include
#include
Huy Le
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2 answers
C++ polymorphism factory How to build function object from its string name and map of parameter
#include
#include
#include
Huy Le
- 1,439
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1 answer
binary comparison not defined when using map
I was looking for a way to have a string[] as a map value, and I found this Stack Overflow question. I attempted to use the std::any type to solve my problem, and I got the error
binary '<': 'const _Ty' does not define this operator or a conversion…
greatusername
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How to Use std::any as mapped_type
I am trying to solve the problem asked yesterday on SO based on this answer.
I have modified the code given here to use std::any instead of void*. The code that i currently have is as follows:
#include
#include
Jason
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CRTP used with std::any vs virtual functions
I am trying to create a compile time polymorphism design that will not require virtual functions with all their drawbacks. However I am struggling with creating simple, effective and easy to understand container that can simulate the ability to hold…
Jirka Zahradnik
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How to get the data type of a std::any variable?
std::any var = 1;
How can you get the type of var?
For example:
std::cout << GetTypeOf(var) << std::endl;
Output:
int
anom
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Generically accessing data from a varying list of attributes within sub-classes while maintaining polymorphic behavior
With the use of constant expressions, parameter packs, lambdas, move semantics, standard containers, and std::any I can easily enough create the following design pattern:
#include
#include
#include
constexpr auto…
Francis Cugler
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Why does the non-pointer std::any_cast not return a reference?
The any_cast() function - say, for a non-const reference operand - has the following signature:
template
T any_cast(any& operand);
Why does this function not return a T& - where the documentation says the returned value is…
einpoklum
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How to find data type in C++17 any vector?
I am trying to find the data type of an element of a vector of any type.
I tried the following code:
#include
#include
#include
#include
int main()
{
std::vector myList;
…
Govinda Totla
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Cannot use library in c++
Description
I'm new to c++. My project needs to use any library, which is a new feature after c++ 17. After updating my compiler following this link. I still encounter an error. Here is the error message and my test code.
g++ version:
g++ (Ubuntu…
Harold
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