f6db0ef946
`TotalEq` is now just an assertion about the `Eq` impl of a type (i.e. `==` is a total equality if a type implements `TotalEq`) so the extra method is just confusing. Also, a new method magically appeared as a hack to allow deriving to assert that the contents of a struct/enum are also TotalEq, because the deriving infrastructure makes it very hard to do anything but create a trait method. (You didn't hear about this horrible work-around from me :(.)
44 lines
1.2 KiB
Rust
44 lines
1.2 KiB
Rust
// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// check that the derived impls for the comparison traits shortcircuit
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// where possible, by having a type that fails when compared as the
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// second element, so this passes iff the instances shortcircuit.
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pub struct FailCmp;
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impl Eq for FailCmp {
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fn eq(&self, _: &FailCmp) -> bool { fail!("eq") }
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}
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impl Ord for FailCmp {
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fn lt(&self, _: &FailCmp) -> bool { fail!("lt") }
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}
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impl TotalEq for FailCmp {}
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impl TotalOrd for FailCmp {
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fn cmp(&self, _: &FailCmp) -> Ordering { fail!("cmp") }
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}
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#[deriving(Eq,Ord,TotalEq,TotalOrd)]
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struct ShortCircuit {
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x: int,
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y: FailCmp
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}
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pub fn main() {
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let a = ShortCircuit { x: 1, y: FailCmp };
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let b = ShortCircuit { x: 2, y: FailCmp };
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assert!(a != b);
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assert!(a < b);
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assert_eq!(a.cmp(&b), ::std::cmp::Less);
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}
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