Correct approach to adding component to entity returned from another function?

[njelly]

I am trying to create a workflow where I can spawn an entity with a base set of components (a sprite sheet bundle, an animation component, some other custom components, etc.). Most entities in the game will use this common set. However, I want to occasionally spawn that entity, and then add onto it a Player component so that the player can take control of it.

I can create a spawn_unit function that takes in mut commands as a param, call it from my spawn_player function, but in my spawn_player function I am unable to add my Player component to this new entity because of rust's borrowing rules (this doesn't compile rustc[E0382] because I've already moved commands, and commands doesn't implement the Copy trait):

fn spawn_player(mut commands: Commands, sprite_sheet: Res<SpriteSheet>) {
    let playerEntity = unit::spawn(
        commands,
        sprite_sheet,
        UnitConfig {
            facing: CardinalDirection4::East,
            position: Vec2::splat(0.),
            move_speed: 3.,
            name: "Player".to_string(),
            sprite_indexes: vec![0, 1],
            sprite_frame_duration: vec![1., 1.],
        },
    );

    commands.entity(playerEntity).insert(Player);
}

If I try another solution using spawn_bundle with UnitBundle like so:

#[derive(Bundle)]
pub struct UnitBundle {
    pub sprite_sheet_bundle: SpriteSheetBundle, // necessary
    // ... some more components go here
}

I can't do this because of this error, which implies it isn't possible to have nested bundles:
the trait bound `bevy::prelude::SpriteSheetBundle: bevy::prelude::Component` is not satisfied

What's the correct approach here? I don't want to copy and paste the same code in multiple places just to add one more additional component for a special case (my player unit).

[wilk10]

To have nested bundles you need to add ‘#[bundle]’ above ‘sprite_sheet_bundle’ in the second approach

[afonsolage]

You can pass Commands a mutable borrowed:

fn spawn(commands: &mut Commands, sprite_sheet: Res<SpriteSheet>,  config UnitConfig) {
    // Do the thing!
}

fn spawn_player(mut commands: Commands, sprite_sheet: Res<SpriteSheet>) {
    let playerEntity = unit::spawn(
        &mut commands, // now borrow checker won't yell at you anymore
        sprite_sheet,
        UnitConfig {
            facing: CardinalDirection4::East,
            position: Vec2::splat(0.),
            move_speed: 3.,
            name: "Player".to_string(),
            sprite_indexes: vec![0, 1],
            sprite_frame_duration: vec![1., 1.],
        },
    );

    commands.entity(playerEntity).insert(Player);
}