FRAME: inherited call weight syntax

[ggwpez]

There was a request to create a less repetitive syntax in the case that calls use the WeightInfo trait to calculate their weight.

This MR adds an attribute to the #[pallet::call] macro in the form of #[pallet::call(weight($type))].
$type will then be prepended to the call name to generate a #[pallet::weight] attribute for each call that does not explicitly annotate one. Alternatively a = token can be used like #[pallet::call(weight = …)].
It is not restricted to use <T as Config>::WeightInfo and could use other types as well (although not advised).

The pallets Alliance, Assets, Balances and example-basic are updated to demonstrate the effect.

Old Syntax

With the pallet::weight annotation above each call.

#[pallet::call]
impl<T: Config> Pallet<T> {

	#[pallet::weight(T::WeightInfo::create())]
	pub fn create(
		...

New Syntax

Intended usage together with a WeightInfo trait. A Config<I> can be used for instanced pallets.

#[pallet::call(weight(<T as Config>::WeightInfo))]
impl<T: Config> Pallet<T> {

	pub fn create(
		...

It is possible to override the inherited value per call:

#[pallet::call(weight = <T as Config>::WeightInfo)]
impl<T: Config> Pallet<T> {

	#[pallet::weight(T::WeightInfo::not_create())]
	pub fn create(
		...

... or using something else entirely (for whatever reason):

struct MyWeight;
impl MyWeight {
	fn create() -> Weight {
		Weight::zero()
	}
}

#[pallet::call(weight(crate::MyWeight))]
impl<T: Config> Pallet<T> {

	pub fn create(
		...

Dev Mode

The inherited weight has precedence over the default weight (=zero).

Follow-ups

• Migrate more pallet
• Write migration script akin to the call-index migration script

TODOs

• Check UI errors
• Tests to assert that the resulting weight value is correct.
• Update / Add docs

[KiChjang]

I prefer making it simple, so something like #[pallet::call(weight($type))] or #[pallet::call(weight = $type)] is more reasonable to me. Putting a prefix there makes people believe that you can put more attributes other than prefix there, which isn't true (yet).

[ggwpez]

I prefer making it simple, so something like #[pallet::call(weight($type))] or #[pallet::call(weight = $type)] is more reasonable to me. Putting a prefix there makes people believe that you can put more attributes other than prefix there, which isn't true (yet).

Yep updated it to use weight($type) and weight = $type.
It stays extensible since we can still use keywords like weight(const 123), if we ever want to.

[sam0x17]

This looks good to me, just a few nits / comments

[ggwpez]

bot rebase

[paritytech-processbot]

Rebased

[ggwpez]

bot merge