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/substrate/substrate-pow-template/substrate/srml/system/src

函数<system::Module<T>>::random_seed()调用

文件夹的名称system也可以是Module的前缀system::Module<T>

//! use srml_support::{decl_module, dispatch::Result};
//! use srml_system::{self as system, ensure_signed};
//!
//! pub trait Trait: system::Trait {}
//!
//! decl_module! {
//! pub struct Module<T: Trait> for enum Call where origin: T::Origin {
//! pub fn system_module_example(origin) -> Result {
//! let _sender = ensure_signed(origin)?;
//! let _random_seed = <system::Module<T>>::random_seed();
//! let _extrinsic_count = <system::Module<T>>::extrinsic_count();
//! Ok(())
//! }
//! }
//! }

2- 函数定义位置
impl<T: Trait> Module<T> {
/// Get the basic random seed.
///
/// In general you won't want to use this, but rather Self::random which
/// allows you to give a subject for the random result and whose value will
/// be independently low-influence random from any other such seeds.
pub fn random_seed() -> T::Hash {
Self::random(&[][..])
}
/// Gets extrinsics count.
pub fn extrinsic_count() -> u32 {
ExtrinsicCount::get().unwrap_or_default()
}