Customize Type Conversion Rules

Sometimes the default auto-conversion tools provided by asbind20 are not enough for handling special user-defined types, it requires user to provide rules for translating them between C++ and AngelScript.

Example for std::byte

The std::byte is defined using enum class byte : unsigned char {};. However, the default logic of type translator will convert enumerations to int because all underlying type of enum in AngelScript is int by default.

For enumerations with custom underlying types, asbind20 provides a utility for quickly implementing the traits.

template<typename Enum>
struct underlying_enum_traits

Utility for quickly implementing type traits for enum with custom underlying type.

Example usage:

// In the global namespace:
template <>
struct asbind20::type_traits<std::byte> :
    public asbind20::underlying_enum_traits<std::byte>
{};

Here is detailed example for how to make std::byte be treated as uint8 by asbind20. You can apply this logic to the type that you want to have customized rules.

// In the global namespace:
template <>
struct asbind20::type_traits<std::byte>
{
    static int set_arg(asIScriptContext* ctx, asUINT arg, std::byte val)
    {
        return ctx->SetArgByte(arg, static_cast<asBYTE>(val));
    }

    static std::byte get_return(asIScriptContext* ctx)
    {
        return static_cast<std::byte>(ctx->GetReturnByte());
    }

    // If you only use native calling convention,
    // you can omit the following two functions.

    static std::byte get_arg(asIScriptGeneric* gen, asUINT arg)
    {
        return static_cast<std::byte>(gen->GetArgByte(arg));
    }

    static int set_return(asIScriptGeneric* gen, std::byte val)
    {
        return gen->SetReturnByte(static_cast<asBYTE>(val));
    }
};

The above conversion rule is already defined in asbind20/type_traits.hpp.

Reference of Conversion Rules Provided by asbind20

template<>
struct type_traits<std::byte> : public asbind20::underlying_enum_traits<std::byte>

template<>
struct type_traits<script_object>