What does Something get(fn something): Option; mean in Rust?

Question

I cloned this template. There is a code like this:

decl_storage! {
    trait Store for Module<T: Trait> as TemplateModule {
        Something get(fn something): Option<u32>;
    }
}

What does Something get(fn something): Option<u32>; mean? Especially what is Something before get(fn something)?

rust macros can define their own specific syntax, so going to the docs for it should be your first step if something looks unfamiliar — kmdreko, Aug 06 '20 at 09:41

score 1 · Accepted Answer · answered Aug 06 '20 at 08:30

Apparently this macro accepts custom syntax, as documented in https://substrate.dev/rustdocs/v2.0.0-rc5/frame_support/macro.decl_storage.html:

Basic storage can be extended as such:

#vis #name get(fn #getter) config(#field_name) build(#closure): #type = #default;

#vis: Set the visibility of the structure. pub or nothing.

#name: Name of the storage item, used as a prefix in storage.

[optional] get(fn #getter): Implements the function #getter to Module.

[optional] config(#field_name): field_name is optional if get is set. Will include the item in GenesisConfig.

[optional] build(#closure): Closure called with storage overlays.

#type: Storage type.

[optional] #default: Value returned when none.

So in your Something is the name of the storage item, used as a prefix in storage.

What does Something get(fn something): Option; mean in Rust?

1 Answers1