Adds ConstGet trait and impl in parameter types

frame/support/src/lib.rs

@@ -50,6 +50,8 @@ pub use paste;
 pub use scale_info;
 #[cfg(feature = "std")]
 pub use serde;
+#[doc(hidden)]
+pub use sp_core::ConstGet;
 pub use sp_core::Void;
 #[doc(hidden)]
 pub use sp_core_hashing_proc_macro;
@@ -338,6 +340,12 @@ macro_rules! parameter_types {
 				Self::get()
 			}
 		}
+
+		impl<_I: From<$type> $(, $ty_params)*> $crate::ConstGet<_I> for $name< $($ty_params),* > {
+			fn get() -> _I {
+				_I::from(Self::get())
+			}
+		}
 	};
 	(IMPL $name:ident, $type:ty, $value:expr $(, $ty_params:ident)*) => {
 		impl< $($ty_params),* > $name< $($ty_params),* > {
@@ -1484,6 +1492,7 @@ pub mod pallet_prelude {
 	};
 	pub use sp_std::marker::PhantomData;
 	pub use sp_weights::Weight;
+	pub use sp_core::ConstGet;
 }
 
 /// The `pallet` attribute macro defines a pallet that can be used with

primitives/core/src/lib.rs

@@ -438,3 +438,11 @@ macro_rules! generate_feature_enabled_macro {
 		}
 	};
 }
+
+/// A trait for querying a single value from a type.
+///
+/// The value should be a constant.
+pub trait ConstGet<T> {
+	/// Return the constant value.
+	fn get() -> T;
+}