switch fn_type_info to a FnMut

src/meta_type.rs

@@ -12,6 +12,11 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+use std::sync::{
+    Arc,
+    Mutex,
+};
+
 use crate::prelude::{
     cmp::Ordering,
     fmt::{
@@ -39,10 +44,10 @@ use crate::{
 ///
 /// This needs a conversion to another representation of types
 /// in order to be serializable.
-#[derive(Clone, Copy)]
+#[derive(Clone)]
 pub struct MetaType {
     /// Function pointer to get type information.
-    fn_type_info: fn() -> Type<MetaForm>,
+    fn_type_info: Arc<Mutex<dyn FnMut() -> Type<MetaForm>>>,
     // The standard type ID (ab)used in order to provide
     // cheap implementations of the standard traits
     // such as `PartialEq`, `PartialOrd`, `Debug` and `Hash`.
@@ -91,15 +96,18 @@ impl MetaType {
         T: TypeInfo + ?Sized + 'static,
     {
         Self {
-            fn_type_info: <T as TypeInfo>::type_info,
+            fn_type_info: Arc::new(Mutex::new(<T as TypeInfo>::type_info)),
             type_id: TypeId::of::<T::Identity>(),
         }
     }
 
     /// Creates a new meta type from the user supplied type id and type info function.
     ///
     /// NOTE: It is the responsibility of the caller to ensure unique type ids per custom type.
-    pub fn new_custom(type_id: u64, fn_type_info: fn() -> Type<MetaForm>) -> Self {
+    pub fn new_custom(
+        type_id: u64,
+        fn_type_info: Arc<Mutex<dyn FnMut() -> Type<MetaForm>>>,
+    ) -> Self {
         Self {
             fn_type_info,
             type_id: TypeId::Custom(type_id),
@@ -108,7 +116,7 @@ impl MetaType {
 
     /// Returns the meta type information.
     pub fn type_info(&self) -> Type<MetaForm> {
-        (self.fn_type_info)()
+        (self.fn_type_info.lock().unwrap())()
     }
 
     /// Returns the type identifier provided by `core::any`.

src/tests.rs

@@ -28,7 +28,13 @@ use crate::{
 };
 use core::marker::PhantomData;
 use scale::Compact;
-use std::num::NonZeroU32;
+use std::{
+    num::NonZeroU32,
+    sync::{
+        Arc,
+        Mutex,
+    },
+};
 
 fn assert_type<T, E>(expected: E)
 where
@@ -371,9 +377,12 @@ fn runtime_meta_type() {
     let custom_u32_type_info = <u32 as TypeInfo>::type_info;
     for i in 0..3 {
         fields.field_mut(|f| {
-            f.ty_meta(MetaType::new_custom(custom_u32_id, custom_u32_type_info))
-                .name(i.to_string())
-                .type_name("custom_u32".to_string())
+            f.ty_meta(MetaType::new_custom(
+                custom_u32_id,
+                Arc::new(Mutex::new(custom_u32_type_info)),
+            ))
+            .name(i.to_string())
+            .type_name("custom_u32".to_string())
         })
     }
     let _ty = TypeBuilder::default()