The Nan::MaybeLocal and Nan::Maybe types are monads that encapsulate v8::Local handles that may be empty.
- Maybe Types
- Maybe Helpers
Nan::Call()Nan::ToDetailString()Nan::ToArrayIndex()Nan::Equals()Nan::NewInstance()Nan::GetFunction()Nan::Set()Nan::DefineOwnProperty()Nan::ForceSet()Nan::Get()Nan::GetPropertyAttributes()Nan::Has()Nan::Delete()Nan::GetPropertyNames()Nan::GetOwnPropertyNames()Nan::SetPrototype()Nan::ObjectProtoToString()Nan::HasOwnProperty()Nan::HasRealNamedProperty()Nan::HasRealIndexedProperty()Nan::HasRealNamedCallbackProperty()Nan::GetRealNamedPropertyInPrototypeChain()Nan::GetRealNamedProperty()Nan::CallAsFunction()Nan::CallAsConstructor()Nan::GetSourceLine()Nan::GetLineNumber()Nan::GetStartColumn()Nan::GetEndColumn()Nan::CloneElementAt()Nan::HasPrivate()Nan::GetPrivate()Nan::SetPrivate()Nan::DeletePrivate()Nan::MakeMaybe()
A Nan::MaybeLocal<T> is a wrapper around v8::Local<T> that enforces a check that determines whether the v8::Local<T> is empty before it can be used.
If an API method returns a Nan::MaybeLocal, the API method can potentially fail either because an exception is thrown, or because an exception is pending, e.g. because a previous API call threw an exception that hasn't been caught yet, or because a v8::TerminateExecution exception was thrown. In that case, an empty Nan::MaybeLocal is returned.
Definition:
template<typename T> class Nan::MaybeLocal {
public:
MaybeLocal();
template<typename S> MaybeLocal(v8::Local<S> that);
bool IsEmpty() const;
template<typename S> bool ToLocal(v8::Local<S> *out);
// Will crash if the MaybeLocal<> is empty.
v8::Local<T> ToLocalChecked();
template<typename S> v8::Local<S> FromMaybe(v8::Local<S> default_value) const;
};See the documentation for v8::MaybeLocal for further details.
A simple Nan::Maybe type, representing an object which may or may not have a value, see https://hackage.haskell.org/package/base/docs/Data-Maybe.html.
If an API method returns a Nan::Maybe<>, the API method can potentially fail either because an exception is thrown, or because an exception is pending, e.g. because a previous API call threw an exception that hasn't been caught yet, or because a v8::TerminateExecution exception was thrown. In that case, a "Nothing" value is returned.
Definition:
template<typename T> class Nan::Maybe {
public:
bool IsNothing() const;
bool IsJust() const;
// Will crash if the Maybe<> is nothing.
T FromJust();
T FromMaybe(const T& default_value);
bool operator==(const Maybe &other);
bool operator!=(const Maybe &other);
};See the documentation for v8::Maybe for further details.
Construct an empty Nan::Maybe type representing nothing.
template<typename T> Nan::Maybe<T> Nan::Nothing();Construct a Nan::Maybe type representing just a value.
template<typename T> Nan::Maybe<T> Nan::Just(const T &t);A helper method for calling a synchronous v8::Function#Call() in a way compatible across supported versions of V8.
For asynchronous callbacks, use Nan::Callback::Call along with an AsyncResource.
Signature:
Nan::MaybeLocal<v8::Value> Nan::Call(v8::Local<v8::Function> fun, v8::Local<v8::Object> recv, int argc, v8::Local<v8::Value> argv[]);
Nan::MaybeLocal<v8::Value> Nan::Call(const Nan::Callback& callback, v8::Local<v8::Object> recv,
int argc, v8::Local<v8::Value> argv[]);
Nan::MaybeLocal<v8::Value> Nan::Call(const Nan::Callback& callback, int argc, v8::Local<v8::Value> argv[]);A helper method for calling v8::Value#ToDetailString() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::String> Nan::ToDetailString(v8::Local<v8::Value> val);A helper method for calling v8::Value#ToArrayIndex() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Uint32> Nan::ToArrayIndex(v8::Local<v8::Value> val);A helper method for calling v8::Value#Equals() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::Equals(v8::Local<v8::Value> a, v8::Local<v8::Value>(b));A helper method for calling v8::Function#NewInstance() and v8::ObjectTemplate#NewInstance() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::Function> h);
Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::Function> h, int argc, v8::Local<v8::Value> argv[]);
Nan::MaybeLocal<v8::Object> Nan::NewInstance(v8::Local<v8::ObjectTemplate> h);A helper method for calling v8::FunctionTemplate#GetFunction() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Function> Nan::GetFunction(v8::Local<v8::FunctionTemplate> t);A helper method for calling v8::Object#Set() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::Set(v8::Local<v8::Object> obj,
v8::Local<v8::Value> key,
v8::Local<v8::Value> value)
Nan::Maybe<bool> Nan::Set(v8::Local<v8::Object> obj,
uint32_t index,
v8::Local<v8::Value> value);A helper method for calling v8::Object#DefineOwnProperty() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::DefineOwnProperty(v8::Local<v8::Object> obj,
v8::Local<v8::String> key,
v8::Local<v8::Value> value,
v8::PropertyAttribute attribs = v8::None);Deprecated, use Nan::DefineOwnProperty().
A helper method for calling v8::Object#ForceSet() in a way compatible across supported versions of V8.
Signature:
NAN_DEPRECATED Nan::Maybe<bool> Nan::ForceSet(v8::Local<v8::Object> obj,
v8::Local<v8::Value> key,
v8::Local<v8::Value> value,
v8::PropertyAttribute attribs = v8::None);A helper method for calling v8::Object#Get() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Value> Nan::Get(v8::Local<v8::Object> obj,
v8::Local<v8::Value> key);
Nan::MaybeLocal<v8::Value> Nan::Get(v8::Local<v8::Object> obj, uint32_t index);A helper method for calling v8::Object#GetPropertyAttributes() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<v8::PropertyAttribute> Nan::GetPropertyAttributes(
v8::Local<v8::Object> obj,
v8::Local<v8::Value> key);A helper method for calling v8::Object#Has() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::Has(v8::Local<v8::Object> obj, v8::Local<v8::String> key);
Nan::Maybe<bool> Nan::Has(v8::Local<v8::Object> obj, uint32_t index);A helper method for calling v8::Object#Delete() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::Delete(v8::Local<v8::Object> obj,
v8::Local<v8::String> key);
Nan::Maybe<bool> Nan::Delete(v8::Local<v8::Object> obj, uint32_t index);A helper method for calling v8::Object#GetPropertyNames() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Array> Nan::GetPropertyNames(v8::Local<v8::Object> obj);A helper method for calling v8::Object#GetOwnPropertyNames() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Array> Nan::GetOwnPropertyNames(v8::Local<v8::Object> obj);A helper method for calling v8::Object#SetPrototype() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::SetPrototype(v8::Local<v8::Object> obj,
v8::Local<v8::Value> prototype);A helper method for calling v8::Object#ObjectProtoToString() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::String> Nan::ObjectProtoToString(v8::Local<v8::Object> obj);A helper method for calling v8::Object#HasOwnProperty() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::HasOwnProperty(v8::Local<v8::Object> obj,
v8::Local<v8::String> key);A helper method for calling v8::Object#HasRealNamedProperty() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::HasRealNamedProperty(v8::Local<v8::Object> obj,
v8::Local<v8::String> key);A helper method for calling v8::Object#HasRealIndexedProperty() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::HasRealIndexedProperty(v8::Local<v8::Object> obj,
uint32_t index);A helper method for calling v8::Object#HasRealNamedCallbackProperty() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::HasRealNamedCallbackProperty(
v8::Local<v8::Object> obj,
v8::Local<v8::String> key);A helper method for calling v8::Object#GetRealNamedPropertyInPrototypeChain() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Value> Nan::GetRealNamedPropertyInPrototypeChain(
v8::Local<v8::Object> obj,
v8::Local<v8::String> key);A helper method for calling v8::Object#GetRealNamedProperty() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Value> Nan::GetRealNamedProperty(v8::Local<v8::Object> obj,
v8::Local<v8::String> key);A helper method for calling v8::Object#CallAsFunction() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Value> Nan::CallAsFunction(v8::Local<v8::Object> obj,
v8::Local<v8::Object> recv,
int argc,
v8::Local<v8::Value> argv[]);A helper method for calling v8::Object#CallAsConstructor() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Value> Nan::CallAsConstructor(v8::Local<v8::Object> obj,
int argc,
v8::Local<v8::Value> argv[]);A helper method for calling v8::Message#GetSourceLine() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::String> Nan::GetSourceLine(v8::Local<v8::Message> msg);A helper method for calling v8::Message#GetLineNumber() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<int> Nan::GetLineNumber(v8::Local<v8::Message> msg);A helper method for calling v8::Message#GetStartColumn() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<int> Nan::GetStartColumn(v8::Local<v8::Message> msg);A helper method for calling v8::Message#GetEndColumn() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<int> Nan::GetEndColumn(v8::Local<v8::Message> msg);A helper method for calling v8::Array#CloneElementAt() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Object> Nan::CloneElementAt(v8::Local<v8::Array> array, uint32_t index);A helper method for calling v8::Object#HasPrivate() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::HasPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);A helper method for calling v8::Object#GetPrivate() in a way compatible across supported versions of V8.
Signature:
Nan::MaybeLocal<v8::Value> Nan::GetPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);A helper method for calling v8::Object#SetPrivate() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::SetPrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key, v8::Local<v8::Value> value);A helper method for calling v8::Object#DeletePrivate() in a way compatible across supported versions of V8.
Signature:
Nan::Maybe<bool> Nan::DeletePrivate(v8::Local<v8::Object> object, v8::Local<v8::String> key);Wraps a v8::Local<> in a Nan::MaybeLocal<>. When called with a Nan::MaybeLocal<> it just returns its argument. This is useful in generic template code that builds on NAN.
Synopsis:
MaybeLocal<v8::Number> someNumber = MakeMaybe(New<v8::Number>(3.141592654));
MaybeLocal<v8::String> someString = MakeMaybe(New<v8::String>("probably"));Signature:
template <typename T, template <typename> class MaybeMaybe>
Nan::MaybeLocal<T> Nan::MakeMaybe(MaybeMaybe<T> v);