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A Key<T> does not always return a value, T; it can return a borrowed value. This is only really exercised by String, which we return by reference. In a situation like this, we cannot have From<T> for KeyOrValue<T> as well as From<Key<T>> for KeyOrValue<T>, because the owned type may be different then the type used by the key. This is fixed by explicitly implementing From in terms of or ValueType trait, so that we can reference the owned type directly.
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futurepaul
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Tests pass, styled_text runs, and the associated type means the rust compiler can guard against mis-use. Thanks for the zulip walkthrough!
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A
Key<T>does not always return a value,T; it can return a borrowedvalue. This is only really exercised by String, which we return by reference.
In a situation like this, we cannot have
From<T>forKeyOrValue<T>as well asFrom<Key<T>>forKeyOrValue<T>, because the owned type may be different then the type used by the key.This is fixed by explicitly implementing
Fromin terms of ourValueTypetrait, so that we can reference the owned type directly.This should unblock #785.
cc @futurepaul, who might be curious about this.