Pass the field type to export functions, if requested

Author: Bromeon

godot-core/src/registry/property.rs

@@ -227,6 +227,7 @@ pub mod export_info_functions {
     use crate::builtin::GString;
     use crate::global::PropertyHint;
     use crate::meta::PropertyHintInfo;
+    use crate::registry::property::Export;
 
     /// Turn a list of variables into a comma separated string containing only the identifiers corresponding
     /// to a true boolean variable.
@@ -412,18 +413,39 @@ pub mod export_info_functions {
     /// Equivalent to `@export_file` in Godot.
     ///
     /// Pass an empty string to have no filter.
-    pub fn export_file<S: AsRef<str>>(filter: S) -> PropertyHintInfo {
-        export_file_inner(false, filter)
+    pub fn export_file<T: Export>(filter: impl AsRef<str>) -> PropertyHintInfo {
+        //T::var_hint()
+        export_file_inner::<T>(false, filter)
+    }
+
+    /// Equivalent to `@export_dir` in Godot.
+    ///
+    /// Pass an empty string to have no filter.
+    pub fn export_dir<T: Export>() -> PropertyHintInfo {
+        PropertyHintInfo {
+            hint: PropertyHint::DIR,
+            hint_string: GString::new(),
+        }
+    }
+
+    /// Equivalent to `@export_global_dir` in Godot.
+    ///
+    /// Pass an empty string to have no filter.
+    pub fn export_global_dir<T: Export>() -> PropertyHintInfo {
+        PropertyHintInfo {
+            hint: PropertyHint::GLOBAL_DIR,
+            hint_string: GString::new(),
+        }
     }
 
     /// Equivalent to `@export_global_file` in Godot.
     ///
     /// Pass an empty string to have no filter.
-    pub fn export_global_file<S: AsRef<str>>(filter: S) -> PropertyHintInfo {
-        export_file_inner(true, filter)
+    pub fn export_global_file<T: Export>(filter: impl AsRef<str>) -> PropertyHintInfo {
+        export_file_inner::<T>(true, filter)
     }
 
-    pub fn export_file_inner<S: AsRef<str>>(global: bool, filter: S) -> PropertyHintInfo {
+    pub fn export_file_inner<T: Export>(global: bool, filter: impl AsRef<str>) -> PropertyHintInfo {
         let hint = if global {
             PropertyHint::GLOBAL_FILE
         } else {
@@ -468,8 +490,6 @@ pub mod export_info_functions {
         export_flags_3d_physics => LAYERS_3D_PHYSICS,
         export_flags_3d_render => LAYERS_3D_RENDER,
         export_flags_3d_navigation => LAYERS_3D_NAVIGATION,
-        export_dir => DIR,
-        export_global_dir => GLOBAL_DIR,
         export_multiline => MULTILINE_TEXT,
         export_color_no_alpha => COLOR_NO_ALPHA,
     );

godot-macros/src/class/data_models/field_export.rs

@@ -388,7 +388,15 @@ macro_rules! quote_export_func {
         Some(quote! {
             ::godot::register::property::export_info_functions::$function_name($($tt)*)
         })
-    }
+    };
+
+    // Passes in a previously declared local `type FieldType = ...` as first generic argument.
+    // Doesn't work if function takes other generic arguments -- in that case it could be converted to a Type<...> parameter.
+    ($function_name:ident < T > ($($tt:tt)*)) => {
+        Some(quote! {
+            ::godot::register::property::export_info_functions::$function_name::<FieldType>($($tt)*)
+        })
+    };
 }
 
 impl ExportType {
@@ -489,20 +497,20 @@ impl ExportType {
             Self::File {
                 global: false,
                 kind: FileKind::Dir,
-            } => quote_export_func! { export_dir() },
+            } => quote_export_func! { export_dir<T>() },
 
             Self::File {
                 global: true,
                 kind: FileKind::Dir,
-            } => quote_export_func! { export_global_dir() },
+            } => quote_export_func! { export_global_dir<T>() },
 
             Self::File {
                 global,
                 kind: FileKind::File { filter },
             } => {
                 let filter = filter.clone().unwrap_or(quote! { "" });
 
-                quote_export_func! { export_file_inner(#global, #filter) }
+                quote_export_func! { export_file_inner<T>(#global, #filter) }
             }
 
             Self::Multiline => quote_export_func! { export_multiline() },

godot-macros/src/class/data_models/property.rs

@@ -154,7 +154,9 @@ pub fn make_property_impl(class_name: &Ident, fields: &Fields) -> TokenStream {
         );
 
         export_tokens.push(quote! {
-            ::godot::register::private::#registration_fn::<#class_name, #field_type>(
+            // This type may be reused in #hint, in case of generic functions.
+            type FieldType = #field_type;
+            ::godot::register::private::#registration_fn::<#class_name, FieldType>(
                 #field_name,
                 #getter_tokens,
                 #setter_tokens,