grade-school: Expect Option<Vec<String>> from grade; add stub file
#256
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Previously, grade was expected to return an `Option<&Vec<String>>`. Because there's a reference inside the lifetime, any implementing School would have been required to maintain ownership of some vectors so that they can be lended out. This unnecessarily restricts the implementation. For example, some implementations may instead have preferred to use BTreeSet. If we expect grade to return `Option<Vec<String>>`, the fact that ownership is given means that a new vector can be made from whatever internal representation is used. Closes #254.
petertseng
changed the title
Option<Vec<String>> from gradeOption<Vec<String>> from grade; add stub file
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Thanks! That makes more sense now! :) |
petertseng
commented
Feb 3, 2017
exercises/grade-school/src/lib.rs
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| unimplemented!() | ||
| } | ||
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| pub fn grade(&self, grade: u32) -> Option<Vec<String>> { |
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It would be nice if, when a constraining choice like this is made, the README or stub file could be explicit about why that interface was chosen.
I failed to do this. It could be something like "If grade returned an Option<&Vec<String>>, the internal implementation would be forced to keep a Vec<String> to lend out. By returning an owned vector instead, the internal implementation is free to use whatever it chooses." This is your chance to suggest whether this text should be added as a comment, or something else.
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Ten days, one definite vote that this improves things, and no objections. I'm merging it. |
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Previously, grade was expected to return an
Option<&Vec<String>>.Because there's a reference inside the lifetime, any implementing School
would have been required to maintain ownership of some vectors so that
they can be lended out. This unnecessarily restricts the implementation.
For example, some implementations may instead have preferred to use
BTreeSet.
If we expect grade to return
Option<Vec<String>>, the fact thatownership is given means that a new vector can be made from whatever
internal representation is used.
Closes #254.