Feature #13009: Implement fetch for Thread.current

• Status: Closed
• Priority: Normal
• Assignee: nobu (Nobuyoshi Nakada)
• Target version: -

[dwbutler (David Butler)]

It's a common idiom to use a fiber-local variable, but return a default value if it hasn't been assigned. Here's an example of Ruby code I would expect to be able to write:

def feature_enabled?
  Thread.current.fetch(:feature_enabled, true)
end

Unfortunately, Thread.current does not implement fetch, like Hash does. So I have to write the more verbose:

def feature_enabled?
  Thread.current.key?(:feature_enabled) ? Thread.current[:feature_enabled] : true
end

Thanks for your consideration!

[shevegen (Robert A. Heiler)]

I can not say whether this feature is important or not, but on the syntax suggestion - I like the above (on the premise that it behaves as .fetch on Hash does; I have not checked this either).

[nobu (Nobuyoshi Nakada)]

Thread.current just returns a Thread instance, so it should be Thread#fetch method.

https://github.com/ruby/ruby/compare/trunk...nobu:feature/Thread%23fetch

[ko1 (Koichi Sasada)]

• Assignee set to nobu (Nobuyoshi Nakada)

2.4? 2.5?

[matz (Yukihiro Matsumoto)]

OK.

Matz

[nobu (Nobuyoshi Nakada)]

• Status changed from Open to Closed

Applied in changeset r57683.

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Thread#fetch

• thread.c (rb_thread_fetch): add new method Thread#fetch.
  [Feature #13009]