Type Definition sp_version::ApiId

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pub type ApiId = [u8; 8];

Expand description

The identity of a particular API interface that the runtime might provide.

The id is generated by hashing the name of the runtime api with BLAKE2 using a hash size of 8 bytes.

The name of the runtime api is the name of the trait when using decl_runtime_apis! macro. So, in the following runtime api declaration:

decl_runtime_apis! {
    trait TestApi {
        fn do_test();
    }
}

The name of the trait would be TestApi and would be taken as input to the BLAKE2 hash function.

As Rust supports renaming of traits, the name of a runtime api given to impl_runtime_apis! doesn’t need to be the same as in decl_runtime_apis!, but only the name in decl_runtime_apis! is the important one!