HaoYang670 opened a new issue, #2001:
URL: https://github.com/apache/arrow-rs/issues/2001
**Is your feature request related to a problem or challenge? Please describe
what you are trying to do.**
This is actually a question or a discussion.
Our current may to implement `Decimal128` and `Decimal256` is that:
```rust
trait BasicDecimal: ... {
const BIT_LENGTH: i32;
}
struct Decimal128 {}
struct Decimal256 {}
impl BasicDecimal for Decimal128 {}
impl BasicDecimal for Decimla256{}
impl Decimal128 {}
```
Actually I find an alternative way to implement this.
```rust
struct Decimal<const BYTE_LENGTH: usize> {
precision: usize,
scale: usize,
value: [u8; BYTE_LENGTH],
}
impl<BYTE_LENGTH> Decimal<BYTE_LENGTH> {}
type Decimal128 = Decimal<16>;
type Decimal256 = Decimal<32>;
impl Decimal128 {}
```
I am not sure which one is better, but these are some pros and cons I
thought:
pros: don't need the basic trait, reducing using macro when coding (better
debugging)
cons: cannot restrict the bit_length to be 128 or 258 because
`const_generic_exprs` is an unstable feature.
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