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* mkdocs: add string_view examples * mkdocs: reference underlying operators * mkdocs: add operator<=> examples * mkdocs: fix style check issues * mkdocs: tweak BJData page * mkdocs: add CMake option hints to macros * mkdocs: fix JSON_DISABLE_ENUM_SERIALIZATION definition * mkdocs: fix link to unit-udt.cpp * mkdocs: fix "Arbitrary Type Conversions" title * mkdocs: link to api/macros/*.md instead of features/macros.md * mkdocs: document JSON_DisableEnumSerialization CMake option * mkdocs: encode required C++ standard in example files * docset: detect gsed/sed * docset: update index * docset: fix CSS patching * docset: add list_missing_pages make target * docset: add list_removed_paths make target * docset: replace page titles with name from index * docset: add install target for Zeal docset browser * Use GCC_TOOL in ci_test_documentation target
77 lines
2.2 KiB
Markdown
77 lines
2.2 KiB
Markdown
# JSON_DIAGNOSTICS
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```cpp
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#define JSON_DIAGNOSTICS /* value */
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```
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This macro enables [extended diagnostics for exception messages](../../home/exceptions.md#extended-diagnostic-messages).
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Possible values are `1` to enable or `0` to disable (default).
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When enabled, exception messages contain a [JSON Pointer](../json_pointer/json_pointer.md) to the JSON value that
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triggered the exception. Note that enabling this macro increases the size of every JSON value by one pointer and adds
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some runtime overhead.
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## Default definition
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The default value is `0` (extended diagnostics are switched off).
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```cpp
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#define JSON_DIAGNOSTICS 0
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```
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When the macro is not defined, the library will define it to its default value.
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## Notes
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!!! note "ABI compatibility"
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As of version 3.11.0, this macro is no longer required to be defined consistently throughout a codebase to avoid
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One Definition Rule (ODR) violations, as the value of this macro is encoded in the namespace, resulting in distinct
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symbol names.
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This allows different parts of a codebase to use different versions or configurations of this library without
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causing improper behavior.
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Where possible, it is still recommended that all code define this the same way for maximum interoperability.
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!!! hint "CMake option"
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Diagnostic messages can also be controlled with the CMake option
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[`JSON_Diagnostics`](../../integration/cmake.md#json_diagnostics) (`OFF` by default)
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which defines `JSON_DIAGNOSTICS` accordingly.
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## Examples
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??? example "Example 1: default behavior"
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```cpp
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--8<-- "examples/diagnostics_standard.cpp"
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```
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Output:
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```
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--8<-- "examples/diagnostics_standard.output"
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```
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This exception can be hard to debug if storing the value `#!c "12"` and accessing it is further apart.
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??? example "Example 2: extended diagnostic messages"
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```cpp
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--8<-- "examples/diagnostics_extended.cpp"
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```
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Output:
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```
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--8<-- "examples/diagnostics_extended.output"
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```
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Now the exception message contains a JSON Pointer `/address/housenumber` that indicates which value has the wrong type.
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## Version history
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- Added in version 3.10.0.
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- As of version 3.11.0 the definition is allowed to vary between translation units.
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