# How to mmap a string

**URL:** <https://discourse.julialang.org/t/how-to-mmap-a-string/39291>\
**Category:** General Usage\
**Tags:** question\
**Created:** [May 11, 2020, 3:20pm UTC](https://discourse.julialang.org/t/how-to-mmap-a-string/39291 "2020-05-11T15:20:54Z")\
**Posts on this page:** 1\
**Showing post:** 15

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**Author:** ![stevengj](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/stevengj/32/71_2.png) [@stevengj](https://discourse.julialang.org/u/stevengj)\
**Post date:** [September 14, 2020, 9:00pm UTC](https://discourse.julialang.org/t/how-to-mmap-a-string/39291/15 "2020-09-14T21:00:36Z")

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> [@arabidopsis](#):
>
> Really would like an enhancement where – a mmapped file that is readonly-- a String should  
> _not_ make a memcpy viz:

What string operations do you need to perform that you couldn’t easily do with a `Vector{UInt8}`? Probably it wouldn’t be hard to define a new `AbstractString` type that supports the operations you need and wraps an mmapped array.

(Doing so with the built-in `String` type would require more low-level plumbing changes.)

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