Why do the setters on MediaRecorderOptions take &mut self?

[allsey87]

The methods of MediaRecorderOptions (e.g. mime_type) take &mut self as a receiver. Is this correct and does it actually guarantee exclusive access seeing that MediaRecorderOptions can be cloned?

Link to the WebIDL: https://github.com/rustwasm/wasm-bindgen/blob/main/crates/web-sys/webidls/enabled/MediaRecorder.webidl

[daxpedda]

This using a builder pattern is probably not the best API design.

What you have to keep in mind is that JsValues are just references to things that live in the JS runtime. cloneing doesn't actually clone the data, it just clones the reference.

You don't really have to be concerned about exclusive access because MediaRecorderOptions isn't Send or Sync, so it can never be called from two places at the same time.

[allsey87]

Indeed, I think would be better if the receiver was &self though. This makes it clearer that the mutability is handled by the type itself. &mut self is misleading in my opinion.

[daxpedda]

I really don't know what the original reason to do so was, but as far as I can see this API is a mistake.

I'm not 100% sure, but I think this can still be changed as it shouldn't be a breaking change, if you would like to make a PR that would be great!

[allsey87]

I'll have a look into it next week