| title |
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4. Supported types |
This is a list of supported types and how they are converted between C++ and Wren. Not everything can be mapped exactly (for example, integers are casted into doubles), so there are some compromises.
| C++ type | Wren type | Return value from Any |
|---|---|---|
| signed char (int8_t) | number (64-bit float) | .as<int8_t>() |
| unsigned char (uint8_t) | number (64-bit float) | .as<uint8_t>() |
| signed short (int16_t) | number (64-bit float) | .as<int16_t>() |
| unsigned short (uint16_t) | number (64-bit float) | .as<uint16_t>() |
| signed int (int32_t) | number (64-bit float) | .as<int32_t>() |
| unsigned int (uint32_t) | number (64-bit float) | .as<uint32_t>() |
| signed long long (int64_t) | number (64-bit float) | .as<int64_t>() |
| unsigned long long (uint64_t) | number (64-bit float) | .as<uint64_t>() |
| float | number (64-bit float) | .as<float>() |
| double | number (64-bit float) | .as<double>() |
| char | number (64-bit float) | .as<char>() |
| char[N] | string | Not possible to get raw char array from Wren, use std::string |
| char* | string | Not possible to get raw char pointer from Wren, use std::string |
| std::string | string | .as<std::string>() |
| std::shared_ptr<T> | T or null | .as<T>() or .as<T*>() or .shared<T>() |
| T (custom types) | foregin class of T | .as<T>() (if copy is supported) or .as<T*>() or .as<T&>() or .shared<T>() |
| C++ type | Reason |
|---|---|
| std::unique_ptr<T> | How would it work if you want to get std::unique_ptr<T>& ? Not possible to implement. |
| std::queue<T> | Can't iterate over the elements without modifying the queue itself. |
The following std containers are supported and will be converted to a Wren type. Read the [11. STL containers]({{< ref "stl.md" >}}) section to understand more about STL containers and how to use them.
{{< hint warning >}} Warning
By default the following STL containers below will be converted to a native type. If you add/bind any of these containers (except optional or variant) as a foregin class via vm.module(...).klass<std::vector<int>>("VectorInt") then that type will no longer be treated as a native type. Only the type you have registered, for example std::vector<int> will be treated as such, other types of the same container, for example std::vector<float> will still be treated as a native list.
Whether the STD container is converted a Wren native list/map or into a Wren foreign class is checked at runtime.
Read the [11. STL containers]({{< ref "types.md" >}}) section to understand how it works. {{< /hint >}}
| C++ type | Wren type | Return value from Any |
|---|---|---|
| std::variant<A, B, C> | A or B or C | .as<A or B or C>() or .as<std::variant<A, B, C>>() |
| std::optional<T> | T or null | .as<T>() (only if not null) or .as<std::optional<T>>() |
| std::vector<T> | native list of T | .as<std::vector<T>>() |
| std::list<T> | native list of T | .as<std::list<T>>() |
| std::deque<T> | native list of T | .as<std::deque<T>>() |
| std::set<T> | native list of T | .as<std::set<T>>() |
| std::unordered_set<T> | native list of T | .as<std::unordered_set<T>>() |
| std::map<std::string, T> | native map of T | .as<std::map<std::string, T>>() |
| std::unordered_map <std::string, T> | native map of T | .as<std::unordered_map <std::string, T>>() |