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Add requirements of TotalEq and TotalOrd #13358

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Apr 7, 2014
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Add requirements of TotalEq and TotalOrd #13358

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cf83ff8
Add requirements of TotalEq and TotalOrd
tbu- Apr 6, 2014
85129e2
Remove use of block comments in src/libstd/cmp.rs
tbu- Apr 6, 2014
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25 changes: 23 additions & 2 deletions src/libstd/cmp.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,18 @@ pub trait Eq {
fn ne(&self, other: &Self) -> bool { !self.eq(other) }
}

/// Trait for equality comparisons where `a == b` and `a != b` are strict inverses.
/**
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Nit: we don't use block comments, use /// on every line.

* Trait for equality comparisons which are [equivalence relations](
* https://en.wikipedia.org/wiki/Equivalence_relation).
*
* This means, that in addition to `a == b` and `a != b` being strict inverses,
* the equality must be (for all `a`, `b` and `c`):
*
* - reflexive: `a == a`;
* - symmetric: `a == b` implies `b == a`; and
* - transitive: `a == b` and `b == c` implies `a == c`.
*/

pub trait TotalEq: Eq {
// FIXME #13101: this method is used solely by #[deriving] to
// assert that every component of a type implements #[deriving]
Expand Down Expand Up @@ -111,7 +122,17 @@ pub enum Ordering {
Greater = 1
}

/// Trait for types that form a total order.
/**
* Trait for types that form a [total order](
* https://en.wikipedia.org/wiki/Total_order).
*
* An order is a total order if it is (for all `a`, `b` and `c`):
*
* - total and antisymmetric: exactly one of `a < b`, `a == b` or `a > b`
* is true; and
* - transitive, `a < b` and `b < c` implies `a < c`. The same must hold for
* both `==` and `>`.
*/
pub trait TotalOrd: TotalEq + Ord {
/// This method returns an ordering between `self` and `other` values.
///
Expand Down