Add ability to ignore field of bundle

[alice-i-cecile]

What problem does this solve or what need does it fill?

Add the ability to ignore a field of a bundle using the #[derive(Bundle)] macro, causing it to not be included in the generated list of components.

This is primarily useful when working with PhantomData.

What solution would you like?

#[derive(Bundle)]
struct GenericBundle<T>{
 transform: Transform,
  #[bundle(ignore)]
  _phantom: PhantomData<T>,
}

Modify the derive Bundle macro to accomplish this :)

Be sure to add this to the Bundle docs as a doc test so this keeps working and can be discovered.

[mockersf]

We already have a #[bundle] attribute, it could be confusing to add a #[bundle(ignore)]. Feel free to find better names either for the existing one or the new one 🙂

[alice-i-cecile]

IMO we should be hygienic and use #[bundle(nest)] to be clearer about what's going on and keep a quasi-namespace for the trait.

[LegNeato]

Serde uses "skip" fwiw

[maccesch]

Almost finished implementing this but I just realized that if you add a #[bundle(ignore)] to a field, this field type has to implement Default or we can't initialize it in the from_components() method that is generated in the macro.

Or am I missing sth here?