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Defined in header <fkYAML/node.hpp>

fkyaml::basic_node::get_value_inplace

template <typename T>
void get_value_inplace(T& value_ref) const noexcept(
    noexcept(ConverterType<T>::from_node(std::declval<const basic_node&>(), std::declval<T&>()))); // (1)

template <typename BasicNodeType>
void get_value_inplace(BasicNodeType& value_ref) const; // (2)

This function converts a fkyaml::basic_node to either of the followings and fills the conversion result into the given value_ref parameter.

  1. a compatible value (copy-constructible)
    The function is equivalent to executing
    ConverterType<T>::from_node(*this, value_ref);
    Unlike the get_value function, this function does not require the template parameter type T to be default-constructible since no instantiation of T is necessary inside the function to return the conversion result.
  2. a fkyaml::basic_node object
    The function is equivalent to executing
    value_ref = *this; // Copy-assigns a current basic_node object.

This function shares internal implementation with the get_value() function.
Thus, all the STL container & scalar types which are supported by that function, are also supported by this function as well.
See the notes there for details.

Differences from get_value()

One crutial difference from the get_value function is, this function does not require the template parameter type T to be default-constructible since no instantiation of T is necessary inside the function to return the conversion result anymore.
So, you might prefer this function, for example, if you already created a T object as a member variable and want to assign a node value to it.

Another is C-style array support.
While get_value cannot accept any kind of C-style array types since returning such array objects is impossible due to its implementation, this function accepts 1D, 2D and 3D arrays. Note that, if T is one of them, the target basic_node object must be a sequence. A type_error is thrown otherwise.

Template Parameters

T
A compatible value type.
BasicNodeType
A basic_node template instance type.

Parameters

value_ref [out]
A storage into which the conversion result is filled.

Examples

Example 
#include <iostream>
#include <fkYAML/node.hpp>

struct not_default_constructible {
    not_default_constructible() = delete;
    explicit not_default_constructible(int v) noexcept
        : value(v) {
    }
    not_default_constructible(const not_default_constructible&) = default;

    int value {0};
};
// Custom implementation of from_node() for not_default_constructible objects.
// This function is called inside get_value_inplace().
// See https://fktn-k.github.io/fkYAML/api/node_value_converter/from_node/ for details.
inline void from_node(const fkyaml::node& n, not_default_constructible& ndc) {
    ndc.value = n.get_value<int>();
}

int main() {
    // create a sequence node.
    fkyaml::node seq = {true, false};

    // fill the node values into a 1D C-style array
    bool bools[2] {};
    seq.get_value_inplace(bools);
    for (auto b : bools) {
        std::cout << std::boolalpha << b << " ";
    }
    std::cout << "\n\n";

    // create an integer scalar node
    fkyaml::node integer = 123;

    // get_value_inplace() accepts a type which is not default constructible.
    not_default_constructible ndc {0};
    integer.get_value_inplace(ndc);
    std::cout << ndc.value << std::endl;

    // of course, you can pass a value of default constructible type as well.
    integer = -123;
    integer.get_value_inplace(ndc.value);
    std::cout << ndc.value << std::endl;

    return 0;
}

output: 

true false 

123
-123

See Also