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Entry APIs should have or_default for V: Default #44324

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jonhoo opened this issue Sep 4, 2017 · 8 comments
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Entry APIs should have or_default for V: Default #44324

jonhoo opened this issue Sep 4, 2017 · 8 comments
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A-collections Area: `std::collection` B-unstable Blocker: Implemented in the nightly compiler and unstable. C-enhancement Category: An issue proposing an enhancement or a PR with one. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.

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@jonhoo
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jonhoo commented Sep 4, 2017

The various Entry APIs (e.g., hash_map::Entry, btree_map::Entry) currently have or_insert, and or_insert_with. However, when V: Default, I believe they should also have an or_default. This would make it nicer to work with things like maps of maps, maps of lists, etc. While it's true that this is equivalent to or_insert_with(Default::default), I would argue that or_default is much more readable.

I'd be happy to take a stab at implementing this, but wanted to air the idea first.
@Mark-Simulacrum Mark-Simulacrum added C-feature-request Category: A feature request, i.e: not implemented / a PR. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. labels Sep 4, 2017
@steveklabnik
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Generally, the way the libs team works is "open a PR if a change is small, open an RFC if a change is big." I'm not on the libs team, but this feels pretty small to me; you already almost have an implementation in the comment!

@jonhoo jonhoo mentioned this issue Sep 5, 2017
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@jonhoo
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jonhoo commented Sep 5, 2017

@steveklabnik PR submitted!

@BurntSushi BurntSushi added the B-unstable Blocker: Implemented in the nightly compiler and unstable. label Sep 11, 2017
bors added a commit that referenced this issue Sep 12, 2017
@bors
Auto merge of #44344 - jonhoo:entry_or_default, r=BurntSushi
817e1b8 
Add or_default to Entry APIs

As argued for in #44324, this PR adds a new `or_default` method to the various `Entry` APIs (currently just for `BTreeMap` and `HashMap`) when `V: Default`. This method is effectively a shorthand for `or_insert_with(Default::default)`.
@TimNN TimNN added the A-collections Area: `std::collection` label Sep 17, 2017
@kennytm kennytm mentioned this issue Sep 23, 2017
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@dtolnay dtolnay removed the C-feature-request Category: A feature request, i.e: not implemented / a PR. label Nov 15, 2017
@dtolnay
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dtolnay commented Nov 15, 2017

An unstable or_default() method was added in #44344. This issue is now the tracking issue for stabilization.

@XAMPPRocky XAMPPRocky added the C-enhancement Category: An issue proposing an enhancement or a PR with one. label Jan 22, 2018
@khuey
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khuey commented Feb 20, 2018

Is there any reason not to just stabilize this?

@SimonSapin
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In Nightly for 6 months, looks good to me to stabilize.

@rfcbot fcp merge

@rfcbot
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rfcbot commented Mar 17, 2018 •
edited by aturon
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Team member @SimonSapin has proposed to merge this. The next step is review by the rest of the tagged teams:

No concerns currently listed.

Once a majority of reviewers approve (and none object), 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.

@rfcbot rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels Mar 17, 2018
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rfcbot commented Mar 19, 2018

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

@rfcbot rfcbot removed the proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. label Mar 19, 2018
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rfcbot commented Mar 29, 2018

The final comment period is now complete.

@Centril Centril added disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. and removed final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. labels May 24, 2018
@GuillaumeGomez GuillaumeGomez mentioned this issue May 26, 2018
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bors added a commit that referenced this issue Jun 10, 2018
@bors
Auto merge of #51079 - GuillaumeGomez:stabilize-entry-or-default, r=S…
900037e 
…imonSapin

Stabilize entry-or-default

Fixes #44324.

cc @SimonSapin
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A-collections Area: `std::collection` B-unstable Blocker: Implemented in the nightly compiler and unstable. C-enhancement Category: An issue proposing an enhancement or a PR with one. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. finished-final-comment-period The final comment period is finished for this PR / Issue. T-libs-api Relevant to the library API team, which will review and decide on the PR/issue.
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