Fix external data loader plugins on Windows

crates/re_data_source/src/data_loader/loader_external.rs

@@ -29,10 +29,21 @@ pub const EXTERNAL_DATA_LOADER_INCOMPATIBLE_EXIT_CODE: i32 = 66;
 pub static EXTERNAL_LOADER_PATHS: Lazy<Vec<std::path::PathBuf>> = Lazy::new(|| {
     re_tracing::profile_function!();
 
+    let dir_separator = if cfg!(target_os = "windows") {
+        ';'
+    } else {
+        ':'
+    };
+
     let dirpaths = std::env::var("PATH")
         .ok()
         .into_iter()
-        .flat_map(|paths| paths.split(':').map(ToOwned::to_owned).collect::<Vec<_>>())
+        .flat_map(|paths| {
+            paths
+                .split(dir_separator)
+                .map(ToOwned::to_owned)
+                .collect::<Vec<_>>()
+        })
         .map(std::path::PathBuf::from);
 
     let mut executables = HashMap::<String, Vec<std::path::PathBuf>>::default();

examples/python/external_data_loader/README.md

@@ -18,4 +18,8 @@
 This is an example executable data-loader plugin for the Rerun Viewer.
 
 It will log Python source code files as markdown documents.
-To try it out, copy it in your $PATH as `rerun-loader-python-file`, then open a Python source file with Rerun (`rerun file.py`).
+
+On Linux & Mac you can simply copy it in your $PATH as `rerun-loader-python-file`, then open a Python source file with Rerun (`rerun file.py`).
+
+On Windows you have to install the script as an executable first and then put the executable under %PATH%.
+One way to do this is to use `pyinstaller`: `pyinstaller .\examples\python\external_data_loader\main.py -n rerun-loader-python-file --onefile`