Trait FmtOrd 

pub trait FmtOrd:
    Display
    + Ord
    + FmtEq { }

A marker trait for types whose ordering is the same as ordering between its Display representation.

When T implements FmtOrd, the following property must be upheld for all a: T and b: T:

assert_eq!(a.cmp(&b), (*format!("{}", a)).cmp(&format!("{}", b)));

In other words (assuming that no ill-defined specialization is involved):

a ⋛ b <-> a.to_string() ⋛ b.to_string()

Colloraries

From str: Ord and the above property, it follows that T satisfies Ord trait’s contract.

Examples

Integer primitives do not satisfy the property.

assert!(42 < 240);
// but...
assert!(42.to_string() > 240.to_string());

Wrapping any Display type with fmt_cmp::Cmp makes it FmtOrd:

assert!(fmt_cmp::Cmp(42) > fmt_cmp::Cmp(240));

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl FmtOrd for Infallible

impl FmtOrd for bool

impl FmtOrd for str

impl FmtOrd for String

Available on crate feature alloc only.

impl<P: Borrow<<P as Deref>::Target> + Deref + Display> FmtOrd for Pin<P>

where P::Target: FmtOrd,

impl<T: FmtOrd + ToOwned + ?Sized> FmtOrd for Cow<'_, T>

where T::Owned: Display,

Available on crate feature alloc only.

impl<T: FmtOrd + ?Sized> FmtOrd for &T

impl<T: FmtOrd + ?Sized> FmtOrd for &mut T

impl<T: FmtOrd + ?Sized> FmtOrd for Box<T>

Available on crate feature alloc only.

impl<T: FmtOrd + ?Sized> FmtOrd for Rc<T>

Available on crate feature alloc only.

impl<T: FmtOrd + ?Sized> FmtOrd for Arc<T>

Available on crate feature alloc only.

Implementors

impl<T: Display + ?Sized> FmtOrd for Cmp<T>