# \#world\_age

**URL:** https://discourse.julialang.org/tag/world-age/1341.md

[Latest](https://discourse.julialang.org/latest.md) · [Categories](https://discourse.julialang.org/categories.md) · [Tags](https://discourse.julialang.org/tags.md)

---

## [World age warning (no @eval) on constructor of different dispatch](https://discourse.julialang.org/t/world-age-warning-no-eval-on-constructor-of-different-dispatch/135947)

<div class="topic-metadata">

**Author:** [@cnaak](https://discourse.julialang.org/u/cnaak)\
**Replies:** 5\
**Last updated:** [March 2, 2026, 2:51pm UTC](https://discourse.julialang.org/t/world-age-warning-no-eval-on-constructor-of-different-dispatch/135947 "2026-03-02T14:51:51Z")

</div>

Updated to julia-1.12 and started a new package. As soon as I defined my first struct with more than one external constructor (nothing fancy, no @evals), I’ve got the world age warning (future error). MWE: struct examp…

---

## [Strict world age conflict with julials](https://discourse.julialang.org/t/strict-world-age-conflict-with-julials/135875)

<div class="topic-metadata">

**Author:** [@psion](https://discourse.julialang.org/u/psion)\
**Replies:** 2\
**Last updated:** [February 26, 2026, 8:14pm UTC](https://discourse.julialang.org/t/strict-world-age-conflict-with-julials/135875 "2026-02-26T20:14:30Z")

</div>

Recently my LSP setup stopped working. I am using julials with nvim-lspconfig in neovim. Here is the main error that I think could be the coulprit. This is taken from the output of :LspLog \[ERROR\]\[2026-02-26 09:40:4…

---

## [World Age for beginners: one way to compile a dynamic language](https://discourse.julialang.org/t/world-age-for-beginners-one-way-to-compile-a-dynamic-language/134402)

<div class="topic-metadata">

**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 2\
**Last updated:** [December 6, 2025, 10:01pm UTC](https://discourse.julialang.org/t/world-age-for-beginners-one-way-to-compile-a-dynamic-language/134402 "2025-12-06T22:01:10Z")

</div>

0. Preface (skippable) The Manual tries to describe the language in a more accessible way, but I’ve felt for a while that world age was unfortunately avoided. In fact, the 1.12 documentation says as much1: World age is…

---

## [World age delay doesn't occur with \`@eval\` in \`begin\` or \`let\` blocks, but does with \`eval\`](https://discourse.julialang.org/t/world-age-delay-doesnt-occur-with-eval-in-begin-or-let-blocks-but-does-with-eval/134367)

<div class="topic-metadata">

**Author:** [@Benny](https://discourse.julialang.org/u/Benny)\
**Replies:** 6\
**Last updated:** [December 5, 2025, 9:58am UTC](https://discourse.julialang.org/t/world-age-delay-doesnt-occur-with-eval-in-begin-or-let-blocks-but-does-with-eval/134367 "2025-12-05T09:58:29Z")

</div>

World age is expected to produce a delay between a method or Task’s compiled code and their changes to the global state, but it wasn’t clear to me what happens in top-level begin or let blocks. Weirdly, there’s this disc…

---

## [Dynamic include file selection with world age constraints in Julia 1.12 - alternatives to conditional include?](https://discourse.julialang.org/t/dynamic-include-file-selection-with-world-age-constraints-in-julia-1-12-alternatives-to-conditional-include/133581)

<div class="topic-metadata">

**Author:** [@sfuerst](https://discourse.julialang.org/u/sfuerst)\
**Replies:** 3\
**Last updated:** [October 31, 2025, 6:36pm UTC](https://discourse.julialang.org/t/dynamic-include-file-selection-with-world-age-constraints-in-julia-1-12-alternatives-to-conditional-include/133581 "2025-10-31T18:36:03Z")

</div>

Hi everyone, I’m facing a challenge with Julia 1.12’s stricter world age semantics. I have a pattern where I conditionally include different implementation variants based on configuration, but this no longer works in Ju…

---

## [Programmatically defining a global variable in a new module](https://discourse.julialang.org/t/programmatically-defining-a-global-variable-in-a-new-module/133188)

<div class="topic-metadata">

**Author:** [@Marco\_Lombardi](https://discourse.julialang.org/u/Marco_Lombardi)\
**Replies:** 17\
**Last updated:** [October 21, 2025, 5:10pm UTC](https://discourse.julialang.org/t/programmatically-defining-a-global-variable-in-a-new-module/133188 "2025-10-21T17:10:59Z")

</div>

I need to be able to programmatically define a new global variable in a module. Till Julia v1.11 I was able to do this as function define\_global() m = Module(:MyModule) Core.eval(m, :(global data)) setglobal…

---

## [World Age Problem Explanation](https://discourse.julialang.org/t/world-age-problem-explanation/9714)

<div class="topic-metadata">

**Author:** [@LS64](https://discourse.julialang.org/u/LS64)\
**Replies:** 21\
**Last updated:** [September 24, 2025, 11:20pm UTC](https://discourse.julialang.org/t/world-age-problem-explanation/9714 "2025-09-24T23:20:20Z")

</div>

Hello. Recently I have faced the “world age problem” several times. That means, after searching for my problems, this website came up with themes like “world age workaround” or “How to Bypass the World Age Problem”. I …

---

## [Malt.jl: Running into world age problems](https://discourse.julialang.org/t/malt-jl-running-into-world-age-problems/123457)

<div class="topic-metadata">

**Author:** [@Parazetamol](https://discourse.julialang.org/u/Parazetamol)\
**Replies:** 1\
**Last updated:** [December 6, 2024, 3:42am UTC](https://discourse.julialang.org/t/malt-jl-running-into-world-age-problems/123457 "2024-12-06T03:42:25Z")

</div>

Hi there, this naive usage of Malt.jl leads to “method too new to be called from this world contex”: module GreatNewModule f()="dummy" end In a separate project (after dev’ed GreatNewModule of course) using GreatNewM…

---

## [Permanently Increase World Age in Local Context](https://discourse.julialang.org/t/permanently-increase-world-age-in-local-context/110257)

<div class="topic-metadata">

**Author:** [@PatrickHaecker](https://discourse.julialang.org/u/PatrickHaecker)\
**Replies:** 5\
**Last updated:** [February 16, 2024, 11:25pm UTC](https://discourse.julialang.org/t/permanently-increase-world-age-in-local-context/110257 "2024-02-16T23:25:17Z")

</div>

Is there a way to permanently increase world age without going to global context? Most of the world age seems to focus on redefining functions. The problem here is different as it is about dynamically defining a type. I…

---

## [World age problem from a package](https://discourse.julialang.org/t/world-age-problem-from-a-package/109104)

<div class="topic-metadata">

**Author:** [@daro.slai](https://discourse.julialang.org/u/daro.slai)\
**Replies:** 11\
**Last updated:** [January 23, 2024, 3:24pm UTC](https://discourse.julialang.org/t/world-age-problem-from-a-package/109104 "2024-01-23T15:24:54Z")

</div>

Hi, I’m having a world age problem in a very weird way, or at least weird enough that I can’t see the similarities with other examples. I have a file simulationFns.jl that defines a few functions such as: using LiiBRA…

---

## [How to call the original Base.show function extended in DataFrames.jl while overriding it?](https://discourse.julialang.org/t/how-to-call-the-original-base-show-function-extended-in-dataframes-jl-while-overriding-it/104437)

<div class="topic-metadata">

**Author:** [@raythurnevoid](https://discourse.julialang.org/u/raythurnevoid)\
**Replies:** 3\
**Last updated:** [October 1, 2023, 3:52am UTC](https://discourse.julialang.org/t/how-to-call-the-original-base-show-function-extended-in-dataframes-jl-while-overriding-it/104437 "2023-10-01T03:52:55Z")

</div>

I’m using the DataFrames.jl package and I want to change the default behavior of show(), I want to print all the rows and columns without passing additional arguments because I want it to work seamlessly while calling di…

---

## [Another world age problem](https://discourse.julialang.org/t/another-world-age-problem/100029)

<div class="topic-metadata">

**Author:** [@user664303](https://discourse.julialang.org/u/user664303)\
**Replies:** 6\
**Last updated:** [June 8, 2023, 1:40am UTC](https://discourse.julialang.org/t/another-world-age-problem/100029 "2023-06-08T01:40:24Z")

</div>

I’m suffering from a world age problem, that Base.invokelatest does not solve. A MWE demonstrating the problem is as follows: module MyModule export myfun myfun(::Type{Int}) = 3 @generated function genfun(::Type{T}) wh…

---

## [Great paper on World Age in Julia](https://discourse.julialang.org/t/great-paper-on-world-age-in-julia/63694)

<div class="topic-metadata">

**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 0\
**Last updated:** [June 28, 2021, 1:21pm UTC](https://discourse.julialang.org/t/great-paper-on-world-age-in-julia/63694 "2021-06-28T13:21:56Z")

</div>

Probably a re-post but I really enjoyed this paper: World Age in Julia Optimizing Method Dispatch in the Presence of Eval (Extended Version) JULIA BELYAKOVA,Northeastern University, USA BENJAMIN CHUNG,Northeastern Univ…

---

## [Using @eval in a function](https://discourse.julialang.org/t/using-eval-in-a-function/89488)

<div class="topic-metadata">

**Author:** [@vitaminace33](https://discourse.julialang.org/u/vitaminace33)\
**Replies:** 17\
**Last updated:** [October 29, 2022, 10:40pm UTC](https://discourse.julialang.org/t/using-eval-in-a-function/89488 "2022-10-29T22:40:23Z")

</div>

Hi! I am trying to extend the methods of a collection of functions programmatically with no partial success. foo(x::Real) = x for f in (:foo,) @eval ($f)(x::Complex) = x' end function fun() foo(x::Real) = x …

---

## [The applicable method may be too new: running in world age 32331, while current world is 32332](https://discourse.julialang.org/t/the-applicable-method-may-be-too-new-running-in-world-age-32331-while-current-world-is-32332/87706)

<div class="topic-metadata">

**Author:** [@Amro](https://discourse.julialang.org/u/Amro)\
**Replies:** 11\
**Last updated:** [September 23, 2022, 8:10pm UTC](https://discourse.julialang.org/t/the-applicable-method-may-be-too-new-running-in-world-age-32331-while-current-world-is-32332/87706 "2022-09-23T20:10:04Z")

</div>

I want to change the field types of R to be of StaticArray. However, I am having the below error. Could you please help me to solve this issue? using LinearAlgebra, StaticArrays Base.@kwdef mutable struct Rs I::Vector…

---

## [What is the best way to avoid world age problem in this case?](https://discourse.julialang.org/t/what-is-the-best-way-to-avoid-world-age-problem-in-this-case/85621)

<div class="topic-metadata">

**Author:** [@Ali\_Vahdati](https://discourse.julialang.org/u/Ali_Vahdati)\
**Replies:** 12\
**Last updated:** [August 28, 2022, 2:01pm UTC](https://discourse.julialang.org/t/what-is-the-best-way-to-avoid-world-age-problem-in-this-case/85621 "2022-08-28T14:01:45Z")

</div>

I am writing a package that uses a YML file as the user interface. Some parameters in the YML file are numbers which are easy to handle. A few parameters need to be functions. I ask the user to put those functions in som…

---

## [How to get the current world age inside a generated function?](https://discourse.julialang.org/t/how-to-get-the-current-world-age-inside-a-generated-function/62969)

<div class="topic-metadata">

**Author:** [@marius311](https://discourse.julialang.org/u/marius311)\
**Replies:** 5\
**Last updated:** [June 15, 2021, 10:57pm UTC](https://discourse.julialang.org/t/how-to-get-the-current-world-age-inside-a-generated-function/62969 "2021-06-15T22:57:37Z")

</div>

A generated function I’m writing needs to determine if its allowed to call a function its been passed, or if that would result in a world-age error (in which case it would fall back to something else). As part of this, I…

---

## [Dynamically Create a Function - Initial Idea with eval failed due to World Age Issue](https://discourse.julialang.org/t/dynamically-create-a-function-initial-idea-with-eval-failed-due-to-world-age-issue/49139)

<div class="topic-metadata">

**Author:** [@roflmaostc](https://discourse.julialang.org/u/roflmaostc)\
**Replies:** 19\
**Last updated:** [October 28, 2020, 2:51pm UTC](https://discourse.julialang.org/t/dynamically-create-a-function-initial-idea-with-eval-failed-due-to-world-age-issue/49139 "2020-10-28T14:51:42Z")

</div>

Hey all, I’m struggling to implement a certain problem. My current situation is the following: Some parts of my project consist of using Tullio functions. Since my arrays can be of arbitrary dimensions and I want to ap…

---

## [Parallel worlds ages don't match](https://discourse.julialang.org/t/parallel-worlds-ages-dont-match/33496)

<div class="topic-metadata">

**Author:** [@pbayer](https://discourse.julialang.org/u/pbayer)\
**Replies:** 5\
**Last updated:** [January 18, 2020, 2:01pm UTC](https://discourse.julialang.org/t/parallel-worlds-ages-dont-match/33496 "2020-01-18T14:01:42Z")

</div>

Im currently developing the multithreading in Simulate.jl. Now – with the current development version – I create a master clock and setup three parallel clocks: using Simulate clk = Clock() multiply!(clk) got 3 threads…

---

## [World age problem](https://discourse.julialang.org/t/world-age-problem/27759)

<div class="topic-metadata">

**Author:** [@ufechner7](https://discourse.julialang.org/u/ufechner7)\
**Replies:** 20\
**Last updated:** [August 21, 2019, 7:55am UTC](https://discourse.julialang.org/t/world-age-problem/27759 "2019-08-21T07:55:30Z")

</div>

In the REPL, the following code works: julia\> func = Meta.parse("x-\>x^2 + 2x - 1") :(x-\>begin #= none:1 =# (x ^ 2 + 2x) - 1 end) julia\> map(eval(func), \[1,3,-1\]) 3-element Array{Int64,1}: 2 …

---

## [Running in world age ... while current world is](https://discourse.julialang.org/t/running-in-world-age-while-current-world-is/23113)

<div class="topic-metadata">

**Author:** [@juliauser](https://discourse.julialang.org/u/juliauser)\
**Replies:** 9\
**Last updated:** [May 20, 2019, 3:56am UTC](https://discourse.julialang.org/t/running-in-world-age-while-current-world-is/23113 "2019-05-20T03:56:15Z")

</div>

Hi, When I run some functions in Julia I obtain this error: The applicable method may be too new: running in world age 26887, while current world is 26894. If I run the code again, there is no error. This is a systemat…

---

## [World age error when parsing function from String](https://discourse.julialang.org/t/world-age-error-when-parsing-function-from-string/11277)

<div class="topic-metadata">

**Author:** [@jocklawrie](https://discourse.julialang.org/u/jocklawrie)\
**Replies:** 4\
**Last updated:** [May 31, 2018, 11:10pm UTC](https://discourse.julialang.org/t/world-age-error-when-parsing-function-from-string/11277 "2018-05-31T23:10:11Z")

</div>

Hi all, I am using DataFrames and wanting to specify intra-row constraints in YAML, which can then be parsed and applied to each row of the data. As an example, the following code works: d = DataFrame( id = UInt.(…

---

## [Is there a way to manually trigger a world\_age update?](https://discourse.julialang.org/t/is-there-a-way-to-manually-trigger-a-world-age-update/7776)

<div class="topic-metadata">

**Author:** [@djsegal](https://discourse.julialang.org/u/djsegal)\
**Replies:** 1\
**Last updated:** [December 15, 2017, 3:14am UTC](https://discourse.julialang.org/t/is-there-a-way-to-manually-trigger-a-world-age-update/7776 "2017-12-15T03:14:41Z")

</div>

Just for reference, this is the kind of world age error you might get: The applicable method may be too new: running in world age 21937, while current world is 22335. The ways around it are: Base.invokelatest Core…

---

## [How to Bypass the World Age Problem](https://discourse.julialang.org/t/how-to-bypass-the-world-age-problem/7012)

<div class="topic-metadata">

**Author:** [@cortner](https://discourse.julialang.org/u/cortner)\
**Replies:** 30\
**Last updated:** [November 19, 2017, 9:58pm UTC](https://discourse.julialang.org/t/how-to-bypass-the-world-age-problem/7012 "2017-11-19T21:58:02Z")

</div>

I finally managed to move some of my codes to v0.6. The World Age problem was a shock as it clashes with one of the main design principles of my code. I’ve read the documentation, and all the discourse topics I could fin…

---

## ["running in world age X, while current world is Y" errors](https://discourse.julialang.org/t/running-in-world-age-x-while-current-world-is-y-errors/5871)

<div class="topic-metadata">

**Author:** [@essenciary](https://discourse.julialang.org/u/essenciary)\
**Replies:** 5\
**Last updated:** [September 15, 2017, 7:56am UTC](https://discourse.julialang.org/t/running-in-world-age-x-while-current-world-is-y-errors/5871 "2017-09-15T07:56:23Z")

</div>

Sorry if I’m missing something obvious but I don’t quite understand why I suddenly get all these errors in v0.6 in all cases where I was successfully dynamically invoking functions before. I did some searching and I dis…