以下特徵可用於比較不同的值。如果欄位會實作這些特徵,您可以針對含有這類欄位的型別衍生所有特徵。
PartialEq
代表部分對等關係,具有必要方法 eq
和提供的方法 ne
。==
和 !=
運算子會呼叫這些方法。
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Eq
代表完整對等關係 (自反、對稱和傳遞性),並且隱含 PartialEq
。需要完整對等關係的函式會使用 Eq
做為特徵界線。
PartialOrd
會透過 partial_cmp
方法定義偏序,可用於實作 <
、<=
、>=
和 >
運算子。
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Ord
是全序,其中 cmp
會傳回 Ordering
。
Speaker Notes
This slide should take about 10 minutes.
PartialEq
可以在不同的型別之間實作,但具有自反性的 Eq
無法:
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實務上一般會衍生這些特徵,但鮮少會實作這些特徵。