Previously, napi_wrap() would only work with objects created from a
constructor returned by napi_define_class(). While the N-API team
was aware of this limitation, it was not clearly documented and is
likely to cause confusion anyway. It's much simpler if addons are
allowed to use any JS object. Also, the specific behavior of the
limitation is difficult to reimplement on other VMs that work
differently from V8.
V8 requires object internal fields to be declared on the object
prototype (which napi_define_class() used to do). Since it's too
late to modify the object prototype by the time napi_wrap() is
called, napi_wrap() now inserts a new object (with the internal
field) into the supplied object's prototype chain. Then it can be
retrieved from there later by napi_unwrap().
This change also includes improvements to the documentation for
napi_create_external(), partly to explain how it is different from
napi_wrap().
PR-URL: https://github.com/nodejs/node/pull/13250
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>
Add support for abi stable module API (N-API) as "Experimental feature".
The goal of this API is to provide a stable Node API for native
module developers. N-API aims to provide ABI compatibility guarantees
across different Node versions and also across different
Node VMs - allowing N-API enabled native modules to just work
across different versions and flavors of Node.js without recompilation.
A more detailed introduction is provided in:
https://github.com/nodejs/node-eps/blob/master/005-ABI-Stable-Module-API.md
and https://github.com/nodejs/abi-stable-node/blob/doc/VM%20Summit.pdf.
The feature, during its experimental state, will be guarded by a runtime
flag "--napi-modules". Only when this flag is added to the command line
will N-API modules along with regular non N-API modules be supported.
The API is defined by the methods in "src/node_api.h" and
"src/node_api_types.h". This is the best
starting point to review the API surface. More documentation will follow.
In addition to the implementation of the API using V8, which is included
in this PR, the API has also been validated against chakracore and that
port is available in
https://github.com/nodejs/abi-stable-node/tree/api-prototype-chakracore-8.x.
The current plan is to provide N-API support in versions 8.X and 6.X
directly. For older versions, such as 4.X or pre N-API versions of 6.X,
we plan to create an external npm module to provide a migration path
that will allow modules targeting older Node.js versions to use the API,
albeit without getting the advantage of not having to recompile.
In addition, we also plan an external npm package with C++ sugar to
simplify the use of the API. The sugar will be in-line only and will
only use the exported N-API methods but is not part of the N-API
itself. The current version is in:
https://github.com/nodejs/node-api.
This PR is a result of work in the abi-stable-node repo:
https://github.com/nodejs/abi-stable-node/tree/doc,
with this PR being the cumulative work on the api-prototype-8.x
branch with the following contributors in alphabetical order:
Author: Arunesh Chandra <arunesh.chandra@microsoft.com>
Author: Gabriel Schulhof <gabriel.schulhof@intel.com>
Author: Hitesh Kanwathirtha <hiteshk@microsoft.com>
Author: Ian Halliday <ianhall@microsoft.com>
Author: Jason Ginchereau <jasongin@microsoft.com>
Author: Michael Dawson <michael_dawson@ca.ibm.com>
Author: Sampson Gao <sampsong@ca.ibm.com>
Author: Taylor Woll <taylor.woll@microsoft.com>
PR-URL: https://github.com/nodejs/node/pull/11975
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
