ceph/src/jaegertracing/opentelemetry-cpp/third_party/nlohmann-json/doc/mkdocs/docs/api/basic_json/get_ref.md

   1 # <small>nlohmann::basic_json::</small>get_ref
   2
   3 ```cpp
   4 template<typename ReferenceType>
   5 ReferenceType get_ref();
   6
   7 template<typename ReferenceType>
   8 const ReferenceType get_ref() const;
   9 ```
  10
  11 Implicit reference access to the internally stored JSON value. No copies are made.
  12
  13 ## Template parameters
  14
  15 `ReferenceType`
  16 :   reference type; must be a reference to [`array_t`](array_t.md), [`object_t`](object_t.md),
  17     [`string_t`](string_t.md), [`boolean_t`](boolean_t.md), [`number_integer_t`](number_integer_t.md), or
  18     [`number_unsigned_t`](number_unsigned_t.md), [`number_float_t`](number_float_t.md), or [`binary_t`](binary_t.md).
  19     Enforced by static assertion.
  20
  21 ## Return value
  22
  23 reference to the internally stored JSON value if the requested reference type fits to the JSON value; throws
  24 [`type_error.303`](../../home/exceptions.md#jsonexceptiontype_error303) otherwise
  25
  26 ## Exception safety
  27
  28 Strong exception safety: if an exception occurs, the original value stays intact.
  29
  30 ## Exceptions
  31
  32 Throws [`type_error.303`](../../home/exceptions.md#jsonexceptiontype_error303) if the requested reference type does not
  33 match the stored JSON value type; example: `"incompatible ReferenceType for get_ref, actual type is binary"`.
  34
  35 ## Complexity
  36
  37 Constant.
  38
  39 ## Notes
  40
  41 !!! warning
  42
  43     Writing data to the referee of the result yields an undefined state.
  44
  45 ## Examples
  46
  47 ??? example
  48
  49     The example shows several calls to `get_ref()`.
  50
  51     ```cpp
  52     --8<-- "examples/get_ref.cpp"
  53     ```
  54
  55     Output:
  56
  57     ```json
  58     --8<-- "examples/get_ref.output"
  59     ```
  60
  61 ## Version history
  62
  63 - Added in version 1.1.0.
  64 - Extended to binary types in version 3.8.0.