Adding 'clone to satisfy the borrow checker' anti-pattern

[simonsan]

Due to inactivity of the author and maintainers not being able to edit the PR I'll move #23 to a new branch in this repository.

Future fixes to the PR will be made on this branch.

[pickfire]

That said, I have seen quite a few blog posts discussing "it is okay to write inefficient code". Those posts even mentioned that clone can be used this way. I wonder if it should be put into the anti-pattern section, we could tell that we should reduce the usage of clone, but I think putting it in anti-pattern is going to make things hard (like what it did to way-cooler).

[simonsan]

That said, I have seen quite a few blog posts discussing "it is okay to write inefficient code". Those posts even mentioned that clone can be used this way. I wonder if it should be put into the anti-pattern section, we could tell that we should reduce the usage of clone, but I think putting it in anti-pattern is going to make things hard (like what it did to way-cooler).

I think it's fine to consider it an anti-pattern, as it's not trying to state that clone is inherently bad, but it is an anti-pattern in regards to satisfy the borrow checker. As long as it is explicitly stated and clear to the reader that this is the topic, it should be ok, I think.

[simonsan]

What I personally still miss here is the influence on performance of clone when used deliberately with bigger Vecs for example. I think that could be stated as a Disadvantage or outcome when using this anti-pattern often. While it should also explicitly state that clone is fine and what I mentioned before, the scope of this anti-pattern should be made crystal clear.

[LukeMathWalker]

My two cents - along the lines of what @pickfire mentioned: we should be very wary of demonizing .clone usage, particularly when we are talking about beginners.
At the same time, it makes sense to call out that "cloning your way out" might work as a short-term solution but might hide bigger issues with the whole architecture of your code that you might have to confront down the line anyway. Maybe linking a balanced article on the topic?

[simonsan]

Maybe linking a balanced article on the topic?

Do you have any recommendations?

[LukeMathWalker]

http://xion.io/post/code/rust-borrowchk-tricks.html perhaps?

[Djazouli]

Hello !
Just to let you know, there is a note at the bottom of the file idioms/mem-replace.md, that referenced to PR #23 , and I believe the changes related to this note should then be included in this PR (I believe the only thing needed is to add a link to the newly created file)

[simonsan]

@pickfire @MarcoIeni Worked in your proposals, want to read over it again? ;)

[MarcoIeni]

That's great, thanks!