const MY_DISCRIMINATOR_SLICE: &[u8] = MY_DISCRIMINATOR.as_slice();

SplDiscriminate 特性

还有一个名为 SplDiscriminate 的特性，它将为您提供 ArrayDiscriminator 常量类型以及判别符的切片表示。这在与 match 语句结合使用时特别方便。

/// A trait for managing 8-byte discriminators in a slab of bytes
pub trait SplDiscriminate {
    /// The 8-byte discriminator as a `[u8; 8]`
    const SPL_DISCRIMINATOR: ArrayDiscriminator;
    /// The 8-byte discriminator as a slice (`&[u8]`)
    const SPL_DISCRIMINATOR_SLICE: &'static [u8] = Self::SPL_DISCRIMINATOR.as_slice();
}

SplDiscriminate 派生宏

《SplDiscriminate》派生宏对于那些希望从特定的字符串字面量中派生他们的8字节判别器的人来说是一个非常有用的工具。通常，您需要运行一个哈希函数来处理字符串字面量，然后复制前8个字节，然后将这些字节硬编码到上面的语句中。

相反，您只需使用《SplDiscriminate》注释一个结构体或枚举，并通过《discriminator_hash_input》属性提供 哈希输入，宏就会自动为您派生8字节判别器！

#[derive(SplDiscriminate)] // Implements `SplDiscriminate` for your struct/enum using your declared string literal hash_input
#[discriminator_hash_input("some_discriminator_hash_input")]
pub struct MyInstruction1 {
    arg1: String,
    arg2: u8,
}

let my_discriminator: ArrayDiscriminator = MyInstruction1::SPL_DISCRIMINATOR;
let my_discriminator_slice: &[u8] = MyInstruction1::SPL_DISCRIMINATOR_SLICE;

注意：使用宏派生的8字节判别器始终是结果哈希字节的前 8个字节。