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Attribute Macro frame_support::pallet_macros::type_value

source ·
#[type_value]
Expand description

Allows defining a struct implementing the Get trait to ease the use of storage types.

This attribute is meant to be used alongside #[pallet::storage] to define a storage’s default value. This attribute can be used multiple times.

Item must be defined as:

#[frame_support::pallet]
mod pallet {
	#[pallet::pallet]
	pub struct Pallet<T>(_);

	#[pallet::storage]
	pub(super) type SomeStorage<T: Config> =
		StorageValue<_, FixedU128, ValueQuery, DefaultForSomeValue>;

	// Define default for ParachainId
	#[pallet::type_value]
	pub fn DefaultForSomeValue() -> FixedU128 {
		FixedU128::from_u32(1)
	}
}

§Macro expansion

The macro renames the function to some internal name, generates a struct with the original name of the function and its generic, and implements Get<$ReturnType> by calling the user defined function.


Documentation for this macro can be found at frame_support::pallet_macros::type_value.