Implement BinWrite for PosValue

[amirbou]

Hey, currently PosValue does not implement BinWrite, which prevents it from being used in structs using #[binrw].

On my machine I implemented (for PosValue<T>):

• BinWrite - by ignoring the pos field
• From<T> - by setting pos=0, making construction easier
• Default if T: Default - by setting pos=0, allowing #[derive(Default)] on structs using PosValue

I added some asserts in pos_value.rs to check everything, and it seems to be working correctly.

May I go ahead and open a PR with the changes?

Thanks!

[csnover]

Hi, thanks for your report! Implementing BinWrite for PosValue<T> seems reasonable to me since this is just a wrapper type for position metadata. I feel less certain about adding From<T> and Default implementations but can’t think of anything off the top of my head that would be hurt by it. Go ahead and open a PR any time!