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Option to make the lru_cache type specific #57436

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Option to make the lru_cache type specific#57436
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rhettinger
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stdlibStandard Library Python modules in the Lib/ directorytype-featureA feature request or enhancement

Description

@rhettinger
rhettinger
opened on Oct 19, 2011
BPO 13227
Nosy @rhettinger, @ncoghlan, @vstinner, @ezio-melotti
Files
  • typed_lru.diff: Add type differentiation to the cache entries
  • typed_lru2.diff: Patch with tests and application to re module
  • typed_lru3.diff: Updated patch with docs
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = 'https://github.com/rhettinger'
closed_at = <Date 2011-10-20.15:59:28.817>
created_at = <Date 2011-10-19.22:06:36.315>
labels = ['type-feature', 'library']
title = 'Option to make the lru_cache type specific'
updated_at = <Date 2011-10-20.15:59:28.815>
user = 'https://github.com/rhettinger'

    bugs.python.org fields:

    activity = <Date 2011-10-20.15:59:28.815>
actor = 'rhettinger'
assignee = 'rhettinger'
closed = True
closed_date = <Date 2011-10-20.15:59:28.817>
closer = 'rhettinger'
components = ['Library (Lib)']
creation = <Date 2011-10-19.22:06:36.315>
creator = 'rhettinger'
dependencies = []
files = ['23473', '23475', '23480']
hgrepos = []
issue_num = 13227
keywords = ['patch']
message_count = 8.0
messages = ['145976', '145985', '145990', '145994', '146007', '146008', '146022', '146023']
nosy_count = 5.0
nosy_names = ['rhettinger', 'ncoghlan', 'vstinner', 'ezio.melotti', 'python-dev']
pr_nums = []
priority = 'low'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue13227'
versions = ['Python 3.3']

    Activity

    1. rhettinger commented on Oct 19, 2011

      @rhettinger
      rhettinger
      on Oct 19, 2011
      ContributorAuthor

      Based on a comment from Andrew Koenig, it is suggested that the lru_cache() offer an option to become type specific so that equal objects of different typed don't get cached to the same entry.

      Here's an example:

      @lru_cache(typed=True)
def square(x):
    print('squaring', x)
    return x * x

for x in [3, 3.0, 3, 3.0]:
    print(square(x))

      Without type specificity, all four calls will return 9 rather than 9. 9.0, 9, 9.0.

      First-pass patch attached.

    2. rhettinger
      self-assigned this
      on Oct 19, 2011
    3. rhettinger
      added
      stdlibStandard Library Python modules in the Lib/ directory
      type-featureA feature request or enhancement
      on Oct 19, 2011

    4. rhettinger commented on Oct 19, 2011

      @rhettinger
      rhettinger
      on Oct 19, 2011
      ContributorAuthor

      Updated patch to include tests and an application to the re module.

    5. vstinner commented on Oct 19, 2011

      @vstinner
      vstinner
      on Oct 19, 2011
      Member

      The patch doesn't update the doc. You may also test type(square(3)). Except of these nits, the patch looks good.

      The typed option is an important feature, and your patch contains a good example of its usage (the re module).

    6. ncoghlan commented on Oct 20, 2011

      @ncoghlan
      ncoghlan
      on Oct 20, 2011
      Contributor

      Features looks good, but the current patch doesn't handle keyword arguments correctly (more details in the Reitveld review).

    7. rhettinger commented on Oct 20, 2011

      @rhettinger
      rhettinger
      on Oct 20, 2011
      ContributorAuthor

      Nick, Ezio, and Victor, thanks for looking at the code.
      Here's an updated the patch:

      • optimization for fast globals() are now keyword-only arguments
      • now types the keyword values, not the key/values tuples
      • expanded tests
      • added the doc update

    8. ncoghlan commented on Oct 20, 2011

      @ncoghlan
      ncoghlan
      on Oct 20, 2011
      Contributor

      Looks good to me (although it took me longer than it should have to figure out why you didn't need to store the keyword argument names a second time)

    9. python-dev commented on Oct 20, 2011

      @python-dev
      python-devmannequin
      on Oct 20, 2011
      Mannequin

      New changeset cba503a2c468 by Raymond Hettinger in branch 'default':
      bpo-13227: Option to make the lru_cache() type specific (suggested by Andrew Koenig).
      http://hg.python.org/cpython/rev/cba503a2c468

    10. rhettinger commented on Oct 20, 2011

      @rhettinger
      rhettinger
      on Oct 20, 2011
      ContributorAuthor

      Victor, Ezio, and Nick, thanks for the review.
      Andrew, thanks for the feature request.

    11. rhettinger
      closed this as completedon Oct 20, 2011
    12. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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