55 lines
3.3 KiB
Markdown
55 lines
3.3 KiB
Markdown
# Supported Macros
|
|
|
|
Some aspects of the library can be configured by defining preprocessor macros before including the `json.hpp` header.
|
|
|
|
## `JSON_CATCH_USER(exception)`
|
|
|
|
This macro overrides `#!cpp catch` calls inside the library. The argument is the type of the exception to catch. As of version 3.8.0, the library only catches `std::out_of_range` exceptions internally to rethrow them as [`json::out_of_range`](../home/exceptions.md#out-of-range) exceptions. The macro is always followed by a scope.
|
|
|
|
See [Switch off exceptions](../home/exceptions.md#switch-off-exceptions) for an example.
|
|
|
|
## `JSON_NOEXCEPTION`
|
|
|
|
Exceptions can be switched off by defining the symbol `JSON_NOEXCEPTION`.
|
|
When defining `JSON_NOEXCEPTION`, `#!cpp try` is replaced by `#!cpp if (true)`,
|
|
`#!cpp catch` is replaced by `#!cpp if (false)`, and `#!cpp throw` is replaced by `#!cpp std::abort()`.
|
|
|
|
The same effect is achieved by setting the compiler flag `-fno-exceptions`.
|
|
|
|
## `JSON_SKIP_UNSUPPORTED_COMPILER_CHECK`
|
|
|
|
When defined, the library will not create a compile error when a known unsupported compiler is detected. This allows to use the library with compilers that do not fully support C++11 and may only work if unsupported features are not used.
|
|
|
|
## `JSON_THROW_USER(exception)`
|
|
|
|
This macro overrides `#!cpp throw` calls inside the library. The argument is the exception to be thrown. Note that `JSON_THROW_USER` should leave the current scope (e.g., by throwing or aborting), as continuing after it may yield undefined behavior.
|
|
|
|
See [Switch off exceptions](../home/exceptions.md#switch-off-exceptions) for an example.
|
|
|
|
## `JSON_TRY_USER`
|
|
|
|
This macro overrides `#!cpp try` calls inside the library. It has no arguments and is always followed by a scope.
|
|
|
|
See [Switch off exceptions](../home/exceptions.md#switch-off-exceptions) for an example.
|
|
|
|
## `NLOHMANN_DEFINE_TYPE_INTRUSIVE(type, member...)`
|
|
|
|
This macro can be used to simplify the serialization/deserialization of types if (1) want to use a JSON object as serialization and (2) want to use the member variable names as object keys in that object.
|
|
|
|
The macro is to be defined inside of the class/struct to create code for. Unlike [`NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE`](#nlohmann_define_type_non_intrusivetype-member), it can access private members.
|
|
The first parameter is the name of the class/struct, and all remaining parameters name the members.
|
|
|
|
See [Simplify your life with macros](arbitrary_types.md#simplify-your-life-with-macros) for an example.
|
|
|
|
## `NLOHMANN_DEFINE_TYPE_NON_INTRUSIVE(type, member...)`
|
|
|
|
This macro can be used to simplify the serialization/deserialization of types if (1) want to use a JSON object as serialization and (2) want to use the member variable names as object keys in that object.
|
|
|
|
The macro is to be defined inside of the namespace of the class/struct to create code for. Private members cannot be accessed. Use [`NLOHMANN_DEFINE_TYPE_INTRUSIVE`](#nlohmann_define_type_intrusivetype-member) in these scenarios.
|
|
The first parameter is the name of the class/struct, and all remaining parameters name the members.
|
|
|
|
See [Simplify your life with macros](arbitrary_types.md#simplify-your-life-with-macros) for an example.
|
|
|
|
## `NLOHMANN_JSON_SERIALIZE_ENUM(type, ...)`
|
|
|
|
This macro simplifies the serialization/deserialization of enum types. See [Specializing enum conversion](enum_conversion.md) for more information.
|