V8 version: 7.6.303.29 OS: Linux Arch: x64 On Thursday, August 29, 2019 at 11:25:24 AM UTC+8, cgsdfc wrote: > > I had this problem with I was writing simple v8 demo. Basically, I want to > bind a C++ `Point` class to javascript so that the following code should > work: > var p = new Point; // Point is function implemented in C++. > print(p.x); > > The `Point` object is expected to have a readonly property `x`. > To achieve that, I performed the following steps: > > 1. Create a `FunctionTemplate` and set its callback to a C++ function. > This serves as the `Point` constructor. The callback uses `External` to > associate a C++ Point to the JS object. > 2. set internal field count to 1 on the `InstanceTemplate` of the > above `FunctionTemplate`. > 3. Attach getter callback implemented in C++ to the point constructor > with `SetAccessor`. The callback uses the `Holder()` method of a > `PropertyCallbackInfo` to get the receiver and then get the C++ Point > object. > 4. Write the above JS code in a C++ string and compile and run it. > > And this will produce an "Internal Field Count Out of Range" error. > Meanwhile, I experimented with the combination of using `Holder` or > `This` and `SetAccessor` or `SetAccessorProperty` and found interesting > results. > The results are: > > 1. SetAccessorProperty works with both `This` and `Holder`. > 2. SetAccessor only works with `This`. > > As I made no use of `Signature`, aren't This and Holder the same thing? > But why it makes a difference w.r.t `SetAccessorProperty` and `SetAccessor`? > In the attachment, I present the code to reproduce this problem and the > modified main BUILD.gn to configure the build. > Anyone who can shed some light on this problem will be greatly appreciated! > > [image: Screenshot from 2019-08-29 11-17-58.png] >
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