# How does RuntimeGeneratedFunctions.jl work?

**URL:** <https://discourse.julialang.org/t/how-does-runtimegeneratedfunctions-jl-work/112925>\
**Category:** General Usage\
**Tags:** runtimegeneratedfunc\
**Created:** [April 14, 2024, 2:22pm UTC](https://discourse.julialang.org/t/how-does-runtimegeneratedfunctions-jl-work/112925 "2024-04-14T14:22:05Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![VPBML](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/vpbml/32/212617_2.png) [@VPBML](https://discourse.julialang.org/u/VPBML)\
**Post date:** [April 14, 2024, 2:22pm UTC](https://discourse.julialang.org/t/how-does-runtimegeneratedfunctions-jl-work/112925/1 "2024-04-14T14:22:05Z")

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Hi,

Could you help me by explaining how does RuntimeGeneratedFunctions.jl work, i.e., how it generates functions without world-age issue? I would really appreciate it.

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**Author:** ![mrufsvold](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mrufsvold/32/31600_2.png) [@mrufsvold](https://discourse.julialang.org/u/mrufsvold)\
**Post date:** [April 14, 2024, 2:51pm UTC](https://discourse.julialang.org/t/how-does-runtimegeneratedfunctions-jl-work/112925/2 "2024-04-14T14:51:29Z")

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I think their docs are pretty good, no? If you have a specific question about something that is unclear in the docs or a specific task you are trying to do but having trouble with, we can be a lot more helpful!

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**Author:** ![lmtzx9h4qqnt](https://avatars.discourse-cdn.com/v4/letter/l/74df32/32.png) [@lmtzx9h4qqnt](https://discourse.julialang.org/u/lmtzx9h4qqnt)\
**Post date:** [September 2, 2024, 4:00am UTC](https://discourse.julialang.org/t/how-does-runtimegeneratedfunctions-jl-work/112925/3 "2024-09-02T04:00:36Z")

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I‘m assuming the question is about how the implementation works, i. e. how it manages to avoid the world age problem. As far as I can tell, this is not explained in the documentation.

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**Author:** ![Benny](https://avatars.discourse-cdn.com/v4/letter/b/49beb7/32.png) [@Benny](https://discourse.julialang.org/u/Benny)\
**Post date:** [September 2, 2024, 9:53am UTC](https://discourse.julialang.org/t/how-does-runtimegeneratedfunctions-jl-work/112925/4 "2024-09-02T09:53:34Z")

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From what I can tell, one pre-existing method of a `@generated` function is compiled with the cached “function” expressions instead of actually `eval`uating a new method or function, which would exist in a newer world age.