From f9180685daa51bf59f67c4adc266d7d09f72ca20 Mon Sep 17 00:00:00 2001
From: MichiRecRoom <1008889+LikeLakers2@users.noreply.github.com>
Date: Tue, 24 Dec 2024 01:15:16 -0500
Subject: [PATCH] Expose access to `SubApps` within `App` (#16952)

# Objective
`SubApps` is visible within the documentation for `bevy_app`. However,
no way of accessing the `SubApps` field in `App` is currently available.

## Solution
Expose two new functions, `App::sub_apps()` and `App::sub_apps_mut()`,
which give immutable and mutable access to `SubApps` respectively.

The other solution is to hide `SubApps`, which I submitted as a PR at
<https://github.com/bevyengine/bevy/pull/16953>.

## Testing
Because of the simplicity of the changes, I only tested by compiling
`bevy_app` - which compiled successfully.

Note: `SubApps`, and its corresponding field on `App`, are not used
outside of `bevy_app` - which means that compiling the other crates is
not necessary.
---
 crates/bevy_app/src/app.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/crates/bevy_app/src/app.rs b/crates/bevy_app/src/app.rs
index a755b978ed081..aa6dfb62e99cd 100644
--- a/crates/bevy_app/src/app.rs
+++ b/crates/bevy_app/src/app.rs
@@ -1058,6 +1058,16 @@ impl App {
         &mut self.sub_apps.main
     }
 
+    /// Returns a reference to the [`SubApps`] collection.
+    pub fn sub_apps(&self) -> &SubApps {
+        &self.sub_apps
+    }
+
+    /// Returns a mutable reference to the [`SubApps`] collection.
+    pub fn sub_apps_mut(&mut self) -> &mut SubApps {
+        &mut self.sub_apps
+    }
+
     /// Returns a reference to the [`SubApp`] with the given label.
     ///
     /// # Panics