clean up cache control attributes #2980

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1. davidism

   added this to the 3.1.0 milestone on Oct 30, 2024
2. davidism

   self-assigned this

   on Oct 30, 2024
3. davidism commented on Oct 30, 2024

   

   davidism

   on Oct 30, 2024

   Last edited by davidism

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   RequestCacheControl.max_stale can have an optional value. Either it's max-stale=int or it's max-stale implying "any age". Right now, Werkzeug's type for this is int | str | None: None if it's not present at all, "*" if it's present with no value, and int otherwise.

   Sourcegraph https://sourcegraph.com/search?q=context:global+lang:Python+%27request.cache_control.max_stale+%3D%3D+%22*%22%27&patternType=keyword&sm=0 finds no uses of cache_control.max_stale == "*". So it appears no one is checking for the no value case. This also just appears to be a lesser-used attribute in general, I barely found any access of cache_control.max_stale at all.

   I'm thinking we simplify the type of this by breaking it into two properties: max_stale: int | None will only handle the (presumably much more common) case where it either has a value or is not present at all. max_stale_any: bool would be true or false based on the presence of the field.

   Searching around a bit, .Net also uses two properties: https://learn.microsoft.com/en-us/dotnet/api/system.net.http.headers.cachecontrolheadervalue.maxstalelimit?view=net-8.0 MaxStale and MaxStaleLimit.

   A thorough check would be:

   if max_stale_any:
       if max_stale is None:
           present no value
       else:
           present with value

   A basic check would be:

   if max_stale is not None:
       present with value

   Currently the check requires isinstance if you don't want a type checker to complain, for both thorough and basic checks:

   if max_stale is not None:
       if isinstance(max_stale, str):
           present no value
       else:
           present with value

   if max_stale is not None and not isinstance(max_stale, str):
       present with value
4. davidism commented on Oct 31, 2024

   

   davidism

   on Oct 31, 2024

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   See #2981 for in depth explanation for the changes made after investigating the code and spec.
5. davidism

   closed this as completedin #2981on Oct 31, 2024
6. github-actions

   locked as resolved and limited conversation to collaborators on Nov 15, 2024