From a5c417748112e9d88d9ca522561e338eb9ba9007 Mon Sep 17 00:00:00 2001 From: Minteck Date: Fri, 25 Feb 2022 18:08:27 +0100 Subject: Initial commit --- node_modules/nan/doc/scopes.md | 73 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 node_modules/nan/doc/scopes.md (limited to 'node_modules/nan/doc/scopes.md') diff --git a/node_modules/nan/doc/scopes.md b/node_modules/nan/doc/scopes.md new file mode 100644 index 0000000..84000ee --- /dev/null +++ b/node_modules/nan/doc/scopes.md @@ -0,0 +1,73 @@ +## Scopes + +A _local handle_ is a pointer to an object. All V8 objects are accessed using handles, they are necessary because of the way the V8 garbage collector works. + +A handle scope can be thought of as a container for any number of handles. When you've finished with your handles, instead of deleting each one individually you can simply delete their scope. + +The creation of `HandleScope` objects is different across the supported versions of V8. Therefore, NAN provides its own implementations that can be used safely across these. + + - Nan::HandleScope + - Nan::EscapableHandleScope + +Also see the V8 Embedders Guide section on [Handles and Garbage Collection](https://github.com/v8/v8/wiki/Embedder%27s%20Guide#handles-and-garbage-collection). + + +### Nan::HandleScope + +A simple wrapper around [`v8::HandleScope`](https://v8docs.nodesource.com/node-8.16/d3/d95/classv8_1_1_handle_scope.html). + +Definition: + +```c++ +class Nan::HandleScope { + public: + Nan::HandleScope(); + static int NumberOfHandles(); +}; +``` + +Allocate a new `Nan::HandleScope` whenever you are creating new V8 JavaScript objects. Note that an implicit `HandleScope` is created for you on JavaScript-accessible methods so you do not need to insert one yourself. + +Example: + +```c++ +// new object is created, it needs a new scope: +void Pointless() { + Nan::HandleScope scope; + v8::Local obj = Nan::New(); +} + +// JavaScript-accessible method already has a HandleScope +NAN_METHOD(Pointless2) { + v8::Local obj = Nan::New(); +} +``` + + +### Nan::EscapableHandleScope + +Similar to [`Nan::HandleScope`](#api_nan_handle_scope) but should be used in cases where a function needs to return a V8 JavaScript type that has been created within it. + +Definition: + +```c++ +class Nan::EscapableHandleScope { + public: + Nan::EscapableHandleScope(); + static int NumberOfHandles(); + template v8::Local Escape(v8::Local value); +} +``` + +Use `Escape(value)` to return the object. + +Example: + +```c++ +v8::Local EmptyObj() { + Nan::EscapableHandleScope scope; + v8::Local obj = Nan::New(); + return scope.Escape(obj); +} +``` + -- cgit