Values and errors

rescripted::Value

Runtime type. Scripts and host functions share this.

Value::Type	C++ construction	Notes
Null	Value() or Value(nullptr)
Bool	Value(true)
Number	Value(3.0) or Value(3)	Stored as double
String	Value("hi") or Value(std::string{})
Array	Value(std::vector<Value>{...})
Map	Value(std::map<std::string, Value>{...})	Custom entity bodies become maps
Function	Value::function(name, HostFn)	Prefer engine.bind

Helpers:

bool is_null() / is_bool() / is_number() / is_string() / is_array() / is_map() / is_function();
bool as_bool();          // truthiness: null/0/"" /empty array are false
double as_number();      // throws RuntimeError if impossible
const std::string& as_string();
std::string to_string(); // always succeeds; arrays/maps print <array>/<map>
Value call(const std::vector<Value>& args);
bool equals(const Value& other); // null/bool/number/string only

as_array() / as_map() have const and non-const overloads; they throw if the type is wrong.

When writing host functions, check args.size() and types yourself. Return Value() for “no result.”

Errors

All of these are std::runtime_error subclasses. Catch rescripted::Error to get everything.

Type	When
Error	Bad engine use: unknown language, missing script, cannot open file, empty language name
ParseError	Invalid JSON or script syntax. line(), column()
RuntimeError	Undefined variable, bad call, division by zero, wrong Value conversion

Do not swallow these in generated host code unless the user asked for a sandbox. Log e.what().

try {
  engine.run(id);
} catch (const rescripted::ParseError& e) {
  // e.line(), e.column(), e.what()
} catch (const rescripted::RuntimeError& e) {
} catch (const rescripted::Error& e) {
}