Detect if this is modified within method

[tqwewe]

I am building an event sourcing system, and need all methods to have a readonly instance of this.. but one method called handle can mutate this.

I am hoping to do this by parsing the AST and detecting if this is being modified in the method, but have no idea if I could reliably do something like this in swc.

Any suggestions would be greatly appreciated 👍

[kdy1]

Are you going to use rust?

[tqwewe]

Yep, my backend is in Rust. I am using TypeScript as a kind of scripting language for the end user. I just want to ensure they will not modify this in their methods they define. (except the method called handle)

[kdy1]

Then I think it will be simple.

Rustdoc of swc contains lots of useful links for rust-side users. https://docs.rs/swc/latest/swc/

[tqwewe]

Would you suggest I use the AST to verify this? I'm just thinking it will be quite difficult to catch situations with Object.assign(this, ...) and other ways to modify this.

[tqwewe]

Another way, probably more simple would be to clone this, and Object.freeze it before calling the users method

[kdy1]

Yeah, it will be quite hard if you want to perfectly block users from modifying this.
Users can pass this using arguments and if then there will be no usage of this