Derive Macro PartialCmp 

#[derive(PartialCmp)]
{
    // Attributes available to this derive:
    #[ord]
}

Derives comparison traits with customizable field behavior.

By default, this macro generates implementations for PartialEq, Eq, PartialOrd, and Ord. All traits respect the same field configuration, ensuring consistent behavior.

Struct-Level Attributes

• #[ord(reverse)] — Reverses the final comparison result
• #[ord(by = [field1(asc), field2(desc)])] — Explicit field comparison order
• #[ord(skip_partial_eq)] — Don’t generate PartialEq (disables all other traits too)
• #[ord(skip_eq)] — Don’t generate Eq (also disables Ord)
• #[ord(skip_partial_ord)] — Don’t generate PartialOrd (also disables Ord)
• #[ord(skip_ord)] — Don’t generate Ord

Field-Level Attributes

• #[ord(skip)] — Exclude this field from all comparisons (both eq and ord)
• #[ord(order = "asc")] or #[ord(order = "desc")] — Sort direction
• #[ord(priority = N)] — Comparison priority (lower = compared first)
• #[ord(compare_with = "path::to::fn")] — Custom comparison function for ordering (signature: fn(&T, &T) -> Ordering)
• #[ord(eq_with = "path::to::fn")] — Custom equality function (signature: fn(&T, &T) -> bool)
• #[ord(none_order = "first")] or #[ord(none_order = "last")] — Option handling

Variant-Level Attributes (Enums)

• #[ord(rank = N)] — Explicit variant ranking (lower = less than)

Custom Comparison Functions

When using compare_with, you can optionally provide eq_with for a custom equality check. If eq_with is not provided, equality is derived from the comparison function (equal when compare_with returns Ordering::Equal).

use partial_cmp_derive::PartialCmp;
use std::cmp::Ordering;

fn cmp_abs(a: &i32, b: &i32) -> Ordering {
    a.abs().cmp(&b.abs())
}

fn eq_abs(a: &i32, b: &i32) -> bool {
    a.abs() == b.abs()
}

#[derive(PartialCmp)]
struct AbsValue {
    #[ord(compare_with = "cmp_abs", eq_with = "eq_abs")]
    value: i32,
}

Example

use partial_cmp_derive::PartialCmp;

#[derive(Debug, PartialCmp)]
#[ord(by = [score(desc), name(asc)])]
struct Player {
    id: u64,      // Not compared (not in `by` list)
    name: String,
    score: u32,
}