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nlohmann
41 lines
1.5 KiB
Markdown
41 lines
1.5 KiB
Markdown
# Modules
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This library has experimental support for C++ modules, introduced in C++20. The library can be imported by writing `import nlohmann.json;` instead of `#include <nlohmann/json.hpp>`.
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Please be aware that the module is experimental and a full test is outstanding, and the exported symbols are subject to change.
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## Requirements
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The `nlohmann.json` module requires that the build system is configured to build and resolve modules when imported. Obviously, as modules were introduced in C++20, this feature can only be used in C++20 and subsequent versions.
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To enable building the `nlohmann.json` module (which is not done by default), the macro `NLOHMANN_JSON_BUILD_MODULES` must be passed to the build system.
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## Example
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When using modules rather than headers, the previous example for creating a `json` object through a JSON file, would instead be:
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```cpp
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import std;
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import nlohmann.json;
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using json = nlohmann::json;
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// ...
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std::ifstream f("example.json");
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json data = json::parse(f);
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```
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## Modules do not export macros
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It should be noted that as modules do not export macros, the `nlohmann.json` module will not export any macros.
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## Exported symbols
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Only the following symbols are exported from `nlohmann.json`:
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- `nlohmann::adl_serializer`
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- `nlohmann::basic_json`
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- `nlohmann::json`
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- `nlohmann::json_pointer`
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- `nlohmann::ordered_json`
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- `nlohmann::ordered_map`
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- `nlohmann::to_string`
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- `nlohmann::literals::json_literals::operator""_json`
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- `nlohmann::literals::json_literals::operator""_json_pointer`
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