Clojure

Adding a :only-keys destructuring option, that throws an exception if there's extra key(s).

Details

  • Type: Enhancement Enhancement
  • Status: Closed Closed
  • Resolution: Declined
  • Affects Version/s: None
  • Fix Version/s: Backlog
  • Component/s: None
  • Labels:
    None

Description

While discussing the issue that prompted ticket [[ticket:236]] on clojure-dev, Richard Newman suggested modifying map destructuring to incorporate a :only-keys. It works exactly like :keys but raises an exception if the destructured map contains other keys. The attached patch shows a possible implementation.

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Assembla Importer added a comment -

Converted from http://www.assembla.com/spaces/clojure/tickets/237
Attachments:
0001-Added-only-keys-destructuring-option-like-keys-but-t.patch - https://www.assembla.com/spaces/clojure/documents/bEnEvg-I4r3OA7eJe5afGb/download/bEnEvg-I4r3OA7eJe5afGb

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Assembla Importer added a comment - Converted from http://www.assembla.com/spaces/clojure/tickets/237 Attachments: 0001-Added-only-keys-destructuring-option-like-keys-but-t.patch - https://www.assembla.com/spaces/clojure/documents/bEnEvg-I4r3OA7eJe5afGb/download/bEnEvg-I4r3OA7eJe5afGb
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Assembla Importer added a comment -

budu said: [file:bEnEvg-I4r3OA7eJe5afGb]: Add :only-keys destructuring option

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Assembla Importer added a comment - budu said: [file:bEnEvg-I4r3OA7eJe5afGb]: Add :only-keys destructuring option
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Assembla Importer added a comment -

richhickey said: Could someone please review this patch? I'm ok with the idea in general, but it seems strange that the :only test would only be available for (non-renaming) :keys destructuring

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Assembla Importer added a comment - richhickey said: Could someone please review this patch? I'm ok with the idea in general, but it seems strange that the :only test would only be available for (non-renaming) :keys destructuring
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Assembla Importer added a comment -

chouser@n01se.net said: One drawback to any such checking is it may prevent code written for a future version of the function that takes more named args from working at all with a previous version of the function. For example 'ref' now accepts :min-history. Code that uses that now would probably work fine with versions of ref that didn't support that knob, but if they checked to prevent extra args they would fail unnecessarily.

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Assembla Importer added a comment - chouser@n01se.net said: One drawback to any such checking is it may prevent code written for a future version of the function that takes more named args from working at all with a previous version of the function. For example 'ref' now accepts :min-history. Code that uses that now would probably work fine with versions of ref that didn't support that knob, but if they checked to prevent extra args they would fail unnecessarily.
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Assembla Importer added a comment -

budu said: Good point, didn't think about that! We could recommend the use of :keys in early development and :only-keys when APIs become very stable.

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Assembla Importer added a comment - budu said: Good point, didn't think about that! We could recommend the use of :keys in early development and :only-keys when APIs become very stable.
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Assembla Importer added a comment -

richhickey said: I don't see the need for this

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Assembla Importer added a comment - richhickey said: I don't see the need for this
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Stuart Sierra added a comment -

Declined. There has been limited support for this ticket. It changes the concept of destructuring to include something more like validation, which it was not intended to support.

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Stuart Sierra added a comment - Declined. There has been limited support for this ticket. It changes the concept of destructuring to include something more like validation, which it was not intended to support.

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    Resolved:
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