Hi All, I like the recently introduced ScopedValue type, but found myself wanting to be able to change it’s default value persistently outside of ScopedValues.with calls. An example for this is that in GitHub - JuliaPluto/PlutoPlotly.jl I default to converting all numbers to Float32 to speed up an…

One of the central premises of ScopedValue is that you observe the same value inside the scoped value as long as you have not executed a with operation along your dynamical execution. It is totally fine to use a RefValue as a value for a ScopedValue. The only “benefit” I see here is that you avoid s…

Thanks @vchuravy for the quick reply. I hadn’t indeed thought about using a RefValue directly. I updated the package mockup to follow the suggestion you gave but I am not so sure anymore whether it’s indeed worth it over just explicitly asking users to pass a RefValue explicitly to a normal Scoped…

I had a similar desire. The @with construct is fine for coding but not very convenient for interactive work. My thought was not to have a mutable value but rather to enter and leave scope with separate commands, something like julia> @newscope x => 2.5 julia> # some interactive coding julia> @…

Yes, that’s kinda what I built ScopedSettings for - a global default value (that can be mutable), integration with Preferences and environment-variables, but behavior like a ScopedValue once a local scope is entered.

Hmm, the semantics are a little different than what I was thinking of but it might serve my needs. How does it differ from the approach described by @disberd and @vchuravy (using a mutable RefValue as a ScopedValue)?

Change `ScopedValue` default outside of `with`

General Usage

ericphanson October 19, 2025, 6:52pm 5

Maybe ANN: ScopedSettings - ScopedValues with malleable global values meets your needs?

Topic		Replies	Views
ANN: ScopedSettings - ScopedValues with malleable global values Package Announcements	0	174	July 22, 2025
What is the use of ScopedValues beyond web authorization? General Usage scopedvalues	14	731	December 16, 2024
Naming of ScopedValues Internals & Design	26	1385	March 7, 2024
Task local storage and scoped values: What they are used for General Usage scopedvalues , task_local_storage	12	780	September 22, 2025
What is a good design for a settable global with a known type? Performance question , performance , design	4	147	October 26, 2024

Change `ScopedValue` default outside of `with`

Related topics