# Copy and clone a custom struct **URL:** \ **Category:** help\ **Created:** [November 22, 2020, 1:17am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782 "2020-11-22T01:17:07Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![mor](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mor](https://users.rust-lang.org/u/mor)\ **Post date:** [November 22, 2020, 1:17am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/1 "2020-11-22T01:17:07Z")
Hi, I am trying to create a copy implementation to a structure with Array2D and a simple array. The compiler doesn't like my implementation. Thanks for any help. Mor ```rust struct Cube1 { pub s1: Array2D, pub s2: Array2D, pub s3: Array2D, pub s4: Array2D, pub s5: Array2D, pub s6: Array2D, pub s1_sides: [i32; 4], pub s2_sides: [i32; 4], pub s3_sides: [i32; 4], pub s4_sides: [i32; 4], pub s5_sides: [i32; 4], pub s6_sides: [i32; 4], } impl Copy for Cube1 { fn copy(&self) -> Cube1 { return Cube1 { s1: Array2D::from_rows(self.s1.as_rows()), s2: Array2D::from_rows(self.s2.as_rows()), s3: Array2D::from_rows(self.s3.as_rows()), s4: Array2D::from_rows(self.s4.as_rows()), s5: Array2D::from_rows(self.s5.as_rows()), s6: Array2D::from_rows(self.s6.as_rows()), s1_sides: self.s1_sides, s2_sides: self.s2_sides, s3_sides: self.s3_sides, s4_sides: self.s4_sides, s5_sides: self.s5_sides, s6_sides: self.s6_sides, } } } ``` The error I am getting: ```rust | 31 | / fn copy(&self) -> Cube1 { 32 | | return Cube1 { 33 | | s1: Array2D::from_rows(self.s1.as_rows()), 34 | | s2: Array2D::from_rows(self.s2.as_rows()), ... | 45 | | } 46 | | } | | _____ ^ not a member of trait `Copy` error[E0204]: the trait `Copy` may not be implemented for this type --> src\cube.rs:29:6 | 15 | pub s1: Array2D, | -------------------- this field does not implement `Copy` 16 | pub s2: Array2D, | -------------------- this field does not implement `Copy` 17 | pub s3: Array2D, | -------------------- this field does not implement `Copy` 18 | pub s4: Array2D, | -------------------- this field does not implement `Copy` 19 | pub s5: Array2D, | -------------------- this field does not implement `Copy` 20 | pub s6: Array2D, | -------------------- this field does not implement `Copy` ... 29 | impl Copy for Cube1 | ^^^^ ``` ---
**Author:** ![Yandros](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/yandros/32/8136_2.png) [@Yandros](https://users.rust-lang.org/u/Yandros)\ **Post date:** [November 22, 2020, 1:29am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/2 "2020-11-22T01:29:54Z")
The [`Copy`](https://doc.rust-lang.org/stable/core/marker/trait.Copy.html) trait has no methods: it is a marker trait used by the compiler not to invalidate "old values" on "move", which are implemented as _shallow bit-wise copies_. The [`Clone`](https://doc.rust-lang.org/stable/core/clone/trait.Clone.html) trait is the one where you can override the "copying" behavior, but only do that if you are not implementing `Copy` already (since when something is `Copy` (and thus `Clone`), it is expected that `Clone` simply delegate to `Copy`). - The error message: ---
**Author:** ![mor](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mor](https://users.rust-lang.org/u/mor)\ **Post date:** [November 22, 2020, 1:35am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/3 "2020-11-22T01:35:40Z")
The clone worked but that mean that I have to do: let d = c.clone(); instead of doing: let d = c; ---
**Author:** ![TomP](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/tomp/32/4735_2.png) [@TomP](https://users.rust-lang.org/u/TomP)\ **Post date:** [November 22, 2020, 1:37am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/4 "2020-11-22T01:37:21Z")
But if `c` can't be copied, because it contains fields that can't be copied, why would you expect that > [@mor](#): > > let d = c would somehow _magically_ copy it? ---
**Author:** ![mor](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mor](https://users.rust-lang.org/u/mor)\ **Post date:** [November 22, 2020, 1:38am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/5 "2020-11-22T01:38:08Z")
I thought that I can implement a copy function like I did for the clone. ---
**Author:** ![mor](https://avatars.discourse-cdn.com/v4/letter/m/edb3f5/32.png) [@mor](https://users.rust-lang.org/u/mor)\ **Post date:** [November 22, 2020, 1:39am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/6 "2020-11-22T01:39:07Z")
Thanks for the help ---
**Author:** ![quinedot](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/quinedot/32/17693_2.png) [@quinedot](https://users.rust-lang.org/u/quinedot)\ **Post date:** [November 22, 2020, 5:59am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/7 "2020-11-22T05:59:44Z")
In addition to `Copy` meaning "a shallow bit for bit copy" as @Yandros said, you can think of this restriction as "no implicit non-`Copy` clones". Implicit clones would interact poorly with the ownership model. ```rust // Hopefully I don't .clone() because I'm just trying to move ownership! struct.frob = complicated_thing; ``` (And Rust tends to prefer potentially expensive operations be explicit to boot.) ---
**Author:** ![system](https://sea1.discourse-cdn.com/flex019/user_avatar/users.rust-lang.org/system/32/51372_2.png) [@system](https://users.rust-lang.org/u/system)\ **Post date:** [February 20, 2021, 5:59am UTC](https://users.rust-lang.org/t/copy-and-clone-a-custom-struct/51782/8 "2021-02-20T05:59:46Z")
Closed on February 20, 2021, 5:59am UTC This topic was automatically closed 90 days after the last reply. We invite you to open a new topic if you have further questions or comments.