# World Age Problem Explanation

**URL:** <https://discourse.julialang.org/t/world-age-problem-explanation/9714>\
**Category:** General Usage\
**Tags:** world\_age\
**Created:** [March 14, 2018, 12:33pm UTC](https://discourse.julialang.org/t/world-age-problem-explanation/9714 "2018-03-14T12:33:07Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![LS64](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ls64/32/3743_2.png) [@LS64](https://discourse.julialang.org/u/LS64)\
**Post date:** [March 15, 2018, 11:15am UTC](https://discourse.julialang.org/t/world-age-problem-explanation/9714/3 "2018-03-15T11:15:19Z")

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Thank you for this information. I’ve read some pages and maybe, I get an idea.

But I need a starting point to understand this issue completely and want to be sure, that I’ve understood this correctly. Can someone please revise or confirm the following?

Every compilation of a function gets a “time stamp”, here known as world age. If I change dependencies to already compiled functions in a new world and execute my code, I get these errors? (In my case, these functions are parts of packages (e.g. Plots), which heightens the level of complexity to me.)  
So, in the end, it is precompilation/recompilation problem, which I can solve by using eval, because @eval forces a new compilation in the latest world (by letting jl\_toplevel\_eval\_flex() decide again, what to do)?

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