Add `then` and `then_with` for ordering. #37054

rednum · 2016-10-09T10:07:49Z

Fixes #37053 (see discussion in rust-lang/rfcs#1677).

rust-highfive · 2016-10-09T10:08:03Z

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apasel422 · 2016-10-09T17:20:41Z

src/libcore/cmp.rs

@@ -245,6 +245,76 @@ impl Ordering {
            Greater => Less,
        }
    }
+
+    /// Chain two orderings.


s/Chain/Chains/

apasel422 · 2016-10-09T17:21:50Z

src/libcore/cmp.rs

+        }
+    }
+
+    /// Chain the ordering with given function.


Chains the ordering with the given function.

rednum · 2016-10-23T21:07:10Z

Fixed doctests, can you please take another look? Should I rename this as discussed in the rust-lang/rfcs#1677 ?

alexcrichton · 2016-10-24T20:32:51Z

@rfcbot fcp merge

Seems like a nifty API to me!

rfcbot · 2016-10-24T20:37:34Z

Team member @alexcrichton has proposed to merge this. The next step is review by the rest of the tagged teams:

Concerns:

~~Naming~~ resolved by Add then and then_with for ordering. #37054 (comment)

Once these reviewers reach consensus, this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

aturon · 2016-10-25T16:30:24Z

@rfcbot concern Naming

This looks like handy functionality, but I think we should consider the naming a bit. I imagine the proposed name is based on analogy with methods on e.g. Option? What this is implementing is something like "lexicographic ordering" (aka "dictionary ordering"), but I'm not sure whether those terms would be helpful/ergonomic to use.

My basic fear is that, when reading code, or does not immediately suggest the actual semantics here.

Unfortunately, nothing better is leaping to mind. Anybody else share this concern, or have alternative ideas?

alexcrichton · 2016-10-25T16:40:16Z

Hm yeah that is true. In retrospect if I initially saw something like Ordering::Less.or(Ordering::Greater) I wouldn't actually know what that would do!

Other thoughts brought up in rust-lang/rfcs#1677 were and/and_then, chain/chain_then.

I sort of like the name chain but agree that the closure-taking variant would sound odd.

rednum · 2016-10-25T20:59:45Z

I've used the name or as analogy to Option, but after giving it a second thought I agree it's not the obvious naming. In Java 8 similar feature is called thenComparing. So I think another possibilty would be to call it then (as also suggested in original RFC) and the functional counterpart then_fn (I think and_then would be a bit confusing, because it already does something else for Option).

aturon · 2016-10-25T22:05:03Z

@rednum then indeed sounds better! I'd suggest then_with for the closure variant.

aturon · 2016-10-31T03:06:54Z

@rfcbot resolved Naming

bors · 2016-11-01T14:09:34Z

☔ The latest upstream changes (presumably #37299) made this pull request unmergeable. Please resolve the merge conflicts.

Conflicts: src/libcoretest/lib.rs

brson · 2016-11-01T20:32:57Z

I think the names without precedent are unfortunate, but can't think of anything better.

rfcbot · 2016-11-01T20:43:30Z

🔔 This is now entering its final comment period, as per the review above. 🔔

psst @alexcrichton, I wasn't able to add the final-comment-period label, please do so.

alexcrichton · 2016-11-01T23:04:53Z

@bors: r+

bors · 2016-11-01T23:04:55Z

📌 Commit 655effe has been approved by alexcrichton

bors · 2016-11-02T12:37:33Z

⌛ Testing commit 655effe with merge acfe959...

Add or and or_else for ordering. Fixes #37053 (see discussion in rust-lang/rfcs#1677).

bors · 2016-11-02T15:44:30Z

Add or and or_else for ordering.

d41c91c

rust-highfive assigned brson Oct 9, 2016

Fix trailing whitespace.

def0b4e

apasel422 reviewed Oct 9, 2016

View reviewed changes

sfackler added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Oct 10, 2016

rednum added 4 commits October 10, 2016 18:54

Fix comments

ca76d43

Fix doctests

43a0226

Add ordering_chaining feature to libcore/lib.rs

c78a212

Actually fix doctests.

634715a

Rename ordering chaining functions.

4e2822c

Merge branch 'master' of https://github.com/rust-lang/rust

655effe

Conflicts: src/libcoretest/lib.rs

bors added a commit that referenced this pull request Nov 2, 2016

Auto merge of #37054 - rednum:master, r=alexcrichton

acfe959

Add or and or_else for ordering. Fixes #37053 (see discussion in rust-lang/rfcs#1677).

bors merged commit 655effe into rust-lang:master Nov 2, 2016

apasel422 mentioned this pull request Nov 19, 2016

Ordering::and_then #34774

Closed

mbrubeck changed the title ~~Add or and or_else for ordering.~~ Add then and then_with for ordering. Sep 29, 2017

mbrubeck unassigned brson Sep 29, 2017

mbrubeck mentioned this pull request Sep 29, 2017

Ordering::and_then rust-lang/rfcs#1677

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Add `then` and `then_with` for ordering. #37054

Add `then` and `then_with` for ordering. #37054

rednum commented Oct 9, 2016

rust-highfive commented Oct 9, 2016

apasel422 Oct 9, 2016

apasel422 Oct 9, 2016 •

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rednum commented Oct 23, 2016

alexcrichton commented Oct 24, 2016

rfcbot commented Oct 24, 2016 •

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aturon commented Oct 25, 2016

alexcrichton commented Oct 25, 2016

rednum commented Oct 25, 2016

aturon commented Oct 25, 2016

aturon commented Oct 31, 2016

bors commented Nov 1, 2016

brson commented Nov 1, 2016

rfcbot commented Nov 1, 2016

alexcrichton commented Nov 1, 2016

bors commented Nov 1, 2016

bors commented Nov 2, 2016

bors commented Nov 2, 2016

Add then and then_with for ordering. #37054

Add then and then_with for ordering. #37054

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rednum commented Oct 9, 2016

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rednum commented Oct 25, 2016

aturon commented Oct 25, 2016

aturon commented Oct 31, 2016

bors commented Nov 1, 2016

brson commented Nov 1, 2016

rfcbot commented Nov 1, 2016

alexcrichton commented Nov 1, 2016

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bors commented Nov 2, 2016

Add `then` and `then_with` for ordering. #37054

Add `then` and `then_with` for ordering. #37054

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