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Why does Unconst exist?
Jul 28, 2021
Tejas
Jul 28, 2021
Ali Çehreli
Jul 28, 2021
Tejas
Jul 28, 2021
user1234
Jul 28, 2021
Tejas
July 28, 2021
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When I initially saw it, I was hopeful that it would allow me to bypass some of the restrictions of const , but it literally just takes a type and strips the const from it, you can't pass a variable to it in order to get rid of const . What use does it serve then?

https://dlang.org/library/std/traits/unconst.html

July 27, 2021
Gravatar of Ali ÇehreliPosted by Ali Çehreli
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On 7/27/21 10:38 PM, Tejas wrote:
> When I initially saw it, I was hopeful that it would allow me to bypass some of the restrictions of ```const``` , but it literally just takes a type and strips the ```const``` from it, you can't pass a variable to it in order to get rid of ```const``` . What use does it serve then?
> 
> https://dlang.org/library/std/traits/unconst.html

Searching under /usr/include/dmd reveals that it is used in the implementations of array property 'dup' and 'copyEmplace', which makes sense: We want copies to be mutable.

Ali
July 28, 2021
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On Wednesday, 28 July 2021 at 05:38:44 UTC, Tejas wrote:

>

When I initially saw it, I was hopeful that it would allow me to bypass some of the restrictions of const , but it literally just takes a type and strips the const from it, you can't pass a variable to it in order to get rid of const . What use does it serve then?

To manipulate types in template metaprogramming.

To remove const from a variable, cast() stuff is shorter than cast(Unconst!(typeof(stuff))) stuff, but it also removes shared and `immutable.

July 28, 2021
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On Wednesday, 28 July 2021 at 05:52:02 UTC, Ali Çehreli wrote:

>

On 7/27/21 10:38 PM, Tejas wrote:

>

When I initially saw it, I was hopeful that it would allow me to bypass some of the restrictions of const , but it literally just takes a type and strips the const from it, you can't pass a variable to it in order to get rid of const . What use does it serve then?

https://dlang.org/library/std/traits/unconst.html

Searching under /usr/include/dmd reveals that it is used in the implementations of array property 'dup' and 'copyEmplace', which makes sense: We want copies to be mutable.

Ali

So it's only useful for the compiler developers? I thought Walter was 100% against introducing any dependency to phobos in dmd? Shouldn't this be part of core.internal package?

July 28, 2021
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On Wednesday, 28 July 2021 at 05:57:31 UTC, user1234 wrote:

>

On Wednesday, 28 July 2021 at 05:38:44 UTC, Tejas wrote:

>

When I initially saw it, I was hopeful that it would allow me to bypass some of the restrictions of const , but it literally just takes a type and strips the const from it, you can't pass a variable to it in order to get rid of const . What use does it serve then?

To manipulate types in template metaprogramming.

To remove const from a variable, cast() stuff is shorter than cast(Unconst!(typeof(stuff))) stuff, but it also removes shared and `immutable.

Oh... that makes sense... then it shouldn't exist in core.internal only, and has a place in phobos. Ignore my last comment.