# New blog post about Julia parametric types and constructors

**URL:** <https://discourse.julialang.org/t/new-blog-post-about-julia-parametric-types-and-constructors/120717>\
**Category:** Teaching & Outreach\
**Tags:** parametric-types, constructors\
**Created:** [September 30, 2024, 11:03am UTC](https://discourse.julialang.org/t/new-blog-post-about-julia-parametric-types-and-constructors/120717 "2024-09-30T11:03:52Z")\
**Posts on this page:** 1\
**Showing post:** 5

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**Author:** ![PatrickHaecker](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/patrickhaecker/32/222891_2.png) [@PatrickHaecker](https://discourse.julialang.org/u/PatrickHaecker)\
**Post date:** [October 7, 2024, 12:58pm UTC](https://discourse.julialang.org/t/new-blog-post-about-julia-parametric-types-and-constructors/120717/5 "2024-10-07T12:58:02Z")

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I really like the tutorial.

In part 1, instead of using `sizeof` in

```julia
println("Generic: ", sizeof(Generic(Int8(1), Int8(2))), " bytes")
println("Parametric: ", sizeof(Parametric(Int8(1), Int8(2))), " bytes")

```

I recommend to use `Base.summarysize` and explain that the resulting 18 bytes are 16 + 2 (pointers + UInt8s). Otherwise readers might wonder how the values are stored in `Generic` if the pointers already take 16 bytes.

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