如何在 Substrate 特定类型和 Rust 原始类型之间进行转换?
How do you convert between Substrate specific types and Rust primitive types?
使用 Substrate 区块链框架,如何在 Substrate 特定类型和 Rust 原始类型之间进行转换,反之亦然?
例如:
- 将时间 (
T::Moment
) 转换为 u64
- 将 u64 转换为
T::Balance
等...
获取最新的 Substrate master
Substrate removed As
支持 From
/Into
。 假设所有类型至少为u32
.
从特征SimpleArithmatic
,实现了以下:
From
: u8
, u16
, u32
TryFrom
: u64
, u128
, usize
TryInto
: u8
, u16
, u32
, u64
, u128
, usize
还提供了另一个特性,以提供符合人体工程学的
当您不关心值是否饱和时的可靠转换。
UniqueSaturatedInto
: u8
, u16
, u32
, u64
, u128
UniqueSaturatedFrom
: u64
, u128
NOTE on SaturatedConversion
from Gav
SaturatedConversion
(saturated_into
and saturated_from
) should not be used unless you know what you're doing, you've thought and considered all options and your use-case implies that saturation is fundamentally correct. The only time I imagine this is the case is deep in runtime arithmetic where you are logically certain it will not overflow, but can't provide a proof because it would depend on consistent pre-existing state.
这意味着从 u32
到 Substrate 特定类型的工作应该很容易:
pub fn u32_to_balance(input: u32) -> T::Balance {
input.into()
}
对于较大的类型,您需要处理 Balance
运行时类型小于可用类型的情况:
pub fn u64_to_balance_option(input: u64) -> Option<T::Balance> {
input.try_into().ok()
}
// Note the warning above about saturated conversions
pub fn u64_to_balance_saturated(input: u64) -> T::Balance {
input.saturated_into()
}
从 T::Balance
转换为 Rust 原语时,您还需要处理不兼容类型之间的转换:
pub fn balance_to_u64(input: T::Balance) -> Option<u64> {
TryInto::<u64>::try_into(input).ok()
}
// Note the warning above about saturated conversions
pub fn balance_to_u64_saturated(input: T::Balance) -> u64 {
input.saturated_into::<u64>()
}
对于 Substrate v1.0
底物提供pub trait As<T>
in the sr-primitives
crate:
/// Simple trait similar to `Into`, except that it can be used to convert numerics between each
/// other.
pub trait As<T> {
/// Convert forward (ala `Into::into`).
fn as_(self) -> T;
/// Convert backward (ala `From::from`).
fn sa(_: T) -> Self;
}
以下是一些如何使用它的工作示例:
impl<T: Trait> Module<T> {
// `as_` will turn T::Balance into a u64
pub fn balance_to_u64(input: T::Balance) -> u64 {
input.as_()
}
// Being explicit, you can convert a `u64` to a T::Balance
// using the `As` trait, with `T: u64`, and then calling `sa`
pub fn u64_to_balance(input: u64) -> T::Balance {
<T::Balance as As<u64>>::sa(input)
}
// You can also let Rust figure out what `T` is
pub fn u64_to_balance_implied(input: u64) -> T::Balance {
<T::Balance as As<_>>::sa(input)
}
// You can also let Rust figure out where `sa` is implemented
pub fn u64_to_balance_implied_more(input: u64) -> T::Balance {
T::Balance::sa(input)
}
}
使用 Substrate 区块链框架,如何在 Substrate 特定类型和 Rust 原始类型之间进行转换,反之亦然?
例如:
- 将时间 (
T::Moment
) 转换为u64
- 将 u64 转换为
T::Balance
等...
获取最新的 Substrate master
Substrate removed As
支持 From
/Into
。 假设所有类型至少为u32
.
从特征SimpleArithmatic
,实现了以下:
From
:u8
,u16
,u32
TryFrom
:u64
,u128
,usize
TryInto
:u8
,u16
,u32
,u64
,u128
,usize
还提供了另一个特性,以提供符合人体工程学的 当您不关心值是否饱和时的可靠转换。
UniqueSaturatedInto
:u8
,u16
,u32
,u64
,u128
UniqueSaturatedFrom
:u64
,u128
NOTE on
SaturatedConversion
from Gav
SaturatedConversion
(saturated_into
andsaturated_from
) should not be used unless you know what you're doing, you've thought and considered all options and your use-case implies that saturation is fundamentally correct. The only time I imagine this is the case is deep in runtime arithmetic where you are logically certain it will not overflow, but can't provide a proof because it would depend on consistent pre-existing state.
这意味着从 u32
到 Substrate 特定类型的工作应该很容易:
pub fn u32_to_balance(input: u32) -> T::Balance {
input.into()
}
对于较大的类型,您需要处理 Balance
运行时类型小于可用类型的情况:
pub fn u64_to_balance_option(input: u64) -> Option<T::Balance> {
input.try_into().ok()
}
// Note the warning above about saturated conversions
pub fn u64_to_balance_saturated(input: u64) -> T::Balance {
input.saturated_into()
}
从 T::Balance
转换为 Rust 原语时,您还需要处理不兼容类型之间的转换:
pub fn balance_to_u64(input: T::Balance) -> Option<u64> {
TryInto::<u64>::try_into(input).ok()
}
// Note the warning above about saturated conversions
pub fn balance_to_u64_saturated(input: T::Balance) -> u64 {
input.saturated_into::<u64>()
}
对于 Substrate v1.0
底物提供pub trait As<T>
in the sr-primitives
crate:
/// Simple trait similar to `Into`, except that it can be used to convert numerics between each
/// other.
pub trait As<T> {
/// Convert forward (ala `Into::into`).
fn as_(self) -> T;
/// Convert backward (ala `From::from`).
fn sa(_: T) -> Self;
}
以下是一些如何使用它的工作示例:
impl<T: Trait> Module<T> {
// `as_` will turn T::Balance into a u64
pub fn balance_to_u64(input: T::Balance) -> u64 {
input.as_()
}
// Being explicit, you can convert a `u64` to a T::Balance
// using the `As` trait, with `T: u64`, and then calling `sa`
pub fn u64_to_balance(input: u64) -> T::Balance {
<T::Balance as As<u64>>::sa(input)
}
// You can also let Rust figure out what `T` is
pub fn u64_to_balance_implied(input: u64) -> T::Balance {
<T::Balance as As<_>>::sa(input)
}
// You can also let Rust figure out where `sa` is implemented
pub fn u64_to_balance_implied_more(input: u64) -> T::Balance {
T::Balance::sa(input)
}
}