Implement Array.length binding

[robertDurst]

Based on the example property in the Design section of the wasm_bindgen book, I reasoned that the Array.length property must be a method, getter, structural.

Also, I learned today that there is in fact a way to trigger an exception with Array.length.

var namelistA = new Array(4294967296); //2 to the 32nd power = 4294967296 
var namelistC = new Array(-100) //negative sign

console.log(namelistA.length); //RangeError: Invalid array length 
console.log(namelistC.length); //RangeError: Invalid array length 

Should I account for this?

I played around with catch however it said Result<u32, JsValue> in not implemented for IntoWasmAbi. Should I implement this? I began to but didn't want to go overboard or do anything too ambitious for my first pr 😅

[robertDurst]

Hmmm... travis crashes.

I am able to replicate this rustup update crash:

$ rustup update                                                                                                                                                                                             ‹system›
info: syncing channel updates for 'stable-x86_64-apple-darwin'
info: syncing channel updates for 'nightly-x86_64-apple-darwin'
info: latest update on 2018-06-22, rust version 1.28.0-nightly (662c70a59 2018-06-21)
info: downloading component 'rustc'
error: failed to parse url: 1.28.0-nightly (662c70a59 2018-06-21)/2018-06-22/rustc-nightly-x86_64-apple-darwin.tar.xz
info: checking for self-updates

       stable-x86_64-apple-darwin unchanged - rustc 1.27.0 (3eda71b00 2018-06-19)
  nightly-x86_64-apple-darwin update failed - rustc 1.28.0-nightly (4a9c58c6b 2018-06-05)

[robertDurst]

Yep this is an issue it looks like: rust-lang/rustup#1443

[jonathan-s]

What does structural mean in wasm-bindgen?

On Fri 22. Jun 2018 at 07:09, Robert Durst ***@***.***> wrote: Yep this is an issue it looks like: rust-lang/rustup#1443 <rust-lang/rustup#1443> — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#291 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACBsEscURH7fKdTudkIgh44uBLBB1zabks5t_Hv-gaJpZM4UzIcT> .

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[robertDurst]

Here is the definition (you'll have to scroll down a bit) from the Design section from the wasm_bindgen book:

this [structural] is a flag to method annotations which indicates that the method being accessed (or property with getters/setters) should be accessed in a structural fashion. For example methods are not accessed through prototype and properties are accessed on the object directly rather than through Object.getOwnPropertyDescriptor

From my understanding, this is for properties that are directly on an object versus properties that are on the prototype.

[fitzgen]

From my understanding, this is for properties that are directly on an object versus properties that are on the prototype.

Yes, this is my understanding as well.

[fitzgen]

Looks great! Thanks :)