Niels Lohmann
330fbead59
* Document clang-tidy exclusions and drop unneeded ones Re-enable every excluded check in a run of clang-tidy 22 over all tests and remove the seven that never fire (cert-err58-cpp, clang-analyzer-webkit.NoUncountedMemberChecker, cppcoreguidelines-virtual-class-destructor, google-readability-function-size, hicpp-function-size, hicpp-no-assembler, readability-function-size). Document the reason for every remaining exclusion at the top of the file. Exclude in advance the checks that only exist in clang-tidy 23 and are noise here (bugprone-signed-bitwise, *-explicit-constructor, readability-trailing-comma, modernize-use-string-view), plus modernize-use-integer-sign-comparison, which needs C++20 std::cmp_less and flags deliberate casts. Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Fix clang-tidy findings in documentation examples and replace redundant aliases Apply clang-tidy fixes to the documentation examples: - performance-avoid-endl: std::endl -> '\n' - readability-qualified-auto: auto -> auto* / const auto* - performance-for-range-copy: copy -> const reference - google-readability-casting: C-style cast -> static_cast Replace redundant aliases (readability-redundant-qualified-alias) such as "using json = nlohmann::json;" with "using nlohmann::json;" in the documentation, README, examples, tests, and benchmarks. Aliases at class scope and aliases of other types (with_base_class_t etc.) are kept. No changes to the library or its public API. All changed examples were compiled and run; their output matches the stored .output files (except max_size and meta, which depend on the platform and compiler). Signed-off-by: Niels Lohmann <mail@nlohmann.me> * Format doc examples with the pinned astyle Signed-off-by: Niels Lohmann <mail@nlohmann.me> --------- Signed-off-by: Niels Lohmann <mail@nlohmann.me>
3.9 KiB
3.9 KiB
JSON_DISABLE_ENUM_SERIALIZATION
#define JSON_DISABLE_ENUM_SERIALIZATION /* value */
When defined to 1, default serialization and deserialization functions for enums are excluded and have to be provided
by the user, for example, using NLOHMANN_JSON_SERIALIZE_ENUM (see
arbitrary type conversions for more details).
Parsing or serializing an enum will result in a compiler error.
This works for both unscoped and scoped enums.
Default definition
The default value is 0.
#define JSON_DISABLE_ENUM_SERIALIZATION 0
Notes
!!! hint "CMake option"
Enum serialization can also be controlled with the CMake option
[`JSON_DisableEnumSerialization`](../../integration/cmake.md#json_disableenumserialization)
(`OFF` by default) which defines `JSON_DISABLE_ENUM_SERIALIZATION` accordingly.
Examples
??? example "Example: Disabled behavior"
The code below forces the library **not** to create default serialization/deserialization functions `from_json` and `to_json`, meaning the code below
**does not** compile.
```cpp
#define JSON_DISABLE_ENUM_SERIALIZATION 1
#include <nlohmann/json.hpp>
using nlohmann::json;
enum class Choice
{
first,
second,
};
int main()
{
// normally invokes to_json serialization function but with JSON_DISABLE_ENUM_SERIALIZATION defined, it does not
const json j = Choice::first;
// normally invokes from_json parse function but with JSON_DISABLE_ENUM_SERIALIZATION defined, it does not
Choice ch = j.get<Choice>();
}
```
??? example "Example: Serialize enum macro"
The code below forces the library **not** to create default serialization/deserialization functions `from_json` and `to_json`, but uses
[`NLOHMANN_JSON_SERIALIZE_ENUM`](nlohmann_json_serialize_enum.md) to parse and serialize the enum.
```cpp
#define JSON_DISABLE_ENUM_SERIALIZATION 1
#include <nlohmann/json.hpp>
using nlohmann::json;
enum class Choice
{
first,
second,
};
NLOHMANN_JSON_SERIALIZE_ENUM(Choice,
{
{ Choice::first, "first" },
{ Choice::second, "second" },
})
int main()
{
// uses user-defined to_json function defined by macro
const json j = Choice::first;
// uses user-defined from_json function defined by macro
Choice ch = j.get<Choice>();
}
```
??? example "Example: User-defined serialization/deserialization functions"
The code below forces the library **not** to create default serialization/deserialization functions `from_json` and `to_json`, but uses user-defined
functions to parse and serialize the enum.
```cpp
#define JSON_DISABLE_ENUM_SERIALIZATION 1
#include <nlohmann/json.hpp>
using nlohmann::json;
enum class Choice
{
first,
second,
};
void from_json(const json& j, Choice& ch)
{
auto value = j.get<std::string>();
if (value == "first")
{
ch = Choice::first;
}
else if (value == "second")
{
ch = Choice::second;
}
}
void to_json(json& j, const Choice& ch)
{
if (ch == Choice::first)
{
j = "first";
}
else if (ch == Choice::second)
{
j = "second";
}
}
int main()
{
// uses user-defined to_json function
const json j = Choice::first;
// uses user-defined from_json function
Choice ch = j.get<Choice>();
}
```
See also
- :simple-cmake: JSON_DisableEnumSerialization - CMake option to control the macro
NLOHMANN_JSON_SERIALIZE_ENUM- serialize/deserialize an enum
Version history
- Added in version 3.11.0.