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📝 document future behavior change

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Niels Lohmann 2022-04-25 20:41:55 +02:00
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47
doc/mkdocs/docs/api/basic_json/operator_ValueType.md
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@ -27,33 +27,44 @@ Linear in the size of the JSON value.
## Notes ## Notes
By default `JSON_EXPLICIT` defined to the empty string, so the signature is: !!! note "Definition of `JSON_EXPLICIT`"
```cpp By default `JSON_EXPLICIT` defined to the empty string, so the signature is:
template<typename ValueType>
operator ValueType() const; ```cpp
``` template<typename ValueType>
operator ValueType() const;
```
If [`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) is set to `0`,
`JSON_EXPLICIT` is defined to `#!cpp explicit`:
If [`JSON_USE_IMPLICIT_CONVERSIONS`](../../features/macros.md#json_use_implicit_conversions) is set to `0`, ```cpp
`JSON_EXPLICIT` is defined to `#!cpp explicit`: template<typename ValueType>
explicit operator ValueType() const;
```
That is, implicit conversions can be switched off by defining
[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) to `0`.
```cpp !!! info "Future behavior change"
template<typename ValueType>
explicit operator ValueType() const; Implicit conversions will be switched off by default in the next major release of the library. That is,
``` `JSON_EXPLICIT` will be set to `#!cpp explicit` by default.
You can prepare existing code by already defining
[`JSON_USE_IMPLICIT_CONVERSIONS`](../macros/json_use_implicit_conversions.md) to `0` and adjust any implicit
conversions by calls to [`get`](../basic_json/get.md).
That is, implicit conversions can be switched off by defining
[`JSON_USE_IMPLICIT_CONVERSIONS`](../../features/macros.md#json_use_implicit_conversions) to `0`.
## Examples ## Examples
??? example ??? example
The example below shows several conversions from JSON values The example below shows several conversions from JSON values to other types. There a few things to note: (1)
to other types. There a few things to note: (1) Floating-point numbers can Floating-point numbers can be converted to integers, (2) A JSON array can be converted to a standard
be converted to integers, (2) A JSON array can be converted to a standard `std::vector<short>`, (3) A JSON object can be converted to C++ associative containers such as
`std::vector<short>`, (3) A JSON object can be converted to C++ `std::unordered_map<std::string, json>`.
associative containers such as `std::unordered_map<std::string, json>`.
```cpp ```cpp
--8<-- "examples/operator__ValueType.cpp" --8<-- "examples/operator__ValueType.cpp"

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doc/mkdocs/docs/api/macros/json_use_implicit_conversions.md
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@ -4,7 +4,8 @@
#define JSON_USE_IMPLICIT_CONVERSIONS /* value */ #define JSON_USE_IMPLICIT_CONVERSIONS /* value */
``` ```
When defined to `0`, implicit conversions are switched off. By default, implicit conversions are switched on. When defined to `0`, implicit conversions are switched off. By default, implicit conversions are switched on. The
value is directly affecting [`operator ValueType`](../basic_json/operator_ValueType.md).
Implicit conversions can also be controlled with the CMake option `JSON_ImplicitConversions` (`ON` by default) which Implicit conversions can also be controlled with the CMake option `JSON_ImplicitConversions` (`ON` by default) which
sets `JSON_USE_IMPLICIT_CONVERSIONS` accordingly. sets `JSON_USE_IMPLICIT_CONVERSIONS` accordingly.
@ -17,6 +18,15 @@ By default, implicit conversions are enabled.
#define JSON_USE_IMPLICIT_CONVERSIONS 1 #define JSON_USE_IMPLICIT_CONVERSIONS 1
``` ```
## Notes
!!! info "Future behavior change"
Implicit conversions will be switched off by default in the next major release of the library.
You can prepare existing code by already defining `JSON_USE_IMPLICIT_CONVERSIONS` to `0` and adjust any implicit
conversions by calls to [`get`](../basic_json/get.md).
## Examples ## Examples
??? example ??? example
@ -36,6 +46,11 @@ By default, implicit conversions are enabled.
auto s = j.get<std::string>(); auto s = j.get<std::string>();
``` ```
## See also
- [**operator ValueType**](../basic_json/operator_ValueType.md) - get a value (implicit)
- [**get**](../basic_json/get.md) - get a value (explicit)
## Version history ## Version history
- Added in version 3.9.0. - Added in version 3.9.0.