Implement replace_with, a function similar to the one provided by the take_mut crate.#36186
Implement replace_with, a function similar to the one provided by the take_mut crate.#36186ticki wants to merge 4 commits intorust-lang:masterfrom
replace_with, a function similar to the one provided by the take_mut crate.#36186Conversation
`take_mut` crate. `replace_with` invokes a closure that will temporarily move out of reference and later place back the value.
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Reopen later. |
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src/libcore/mem.rs
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| fn drop(&mut self) { | ||
| // To avoid unwinding, we abort the program, which ensures that the destructor of the | ||
| // invalidated value isn't runned. | ||
| unsafe { intrinsics::abort(); } |
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It would be nice to print a message here, ideally even a backtrace (if RUST_BACKTRACE is set).
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Agreed. Unfortunately, there is no possibility to do so in libcore.
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Aha. Well, perhaps libstd could do so instead of providing a straight re-export.
src/libcore/mem.rs
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| impl Drop for ExitGuard { | ||
| fn drop(&mut self) { | ||
| // To avoid unwinding, we abort the program, which ensures that the destructor of the | ||
| // invalidated value isn't runned. |
| pub fn replace_with<T, F>(val: &mut T, replace: F) | ||
| where F: FnOnce(T) -> T { | ||
| // Guard against unwinding. Note that this is critical to safety, to avoid the value behind the | ||
| // reference `val` is not dropped twice during unwinding. |
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Instead of "to avoid the value...is not dropped", maybe " to avoid the value...being dropped" or just "to avoid dropping the value..."
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your example in the comment uses mem::replace instead of mem::replace_with
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Everything should be fixed now. |
| } | ||
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| // Forget the guard, to avoid panicking. | ||
| mem::forget(guard); |
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Fails with "Use of undeclared type or module mem". I believe this should just be forget(guard);
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Why is this PR closed? |
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It was the proposed implementation for an RFC which was closed:
rust-lang/rfcs#1736
…On Fri, Oct 30, 2020 at 1:16 PM TonalidadeHidrica ***@***.***> wrote:
Why is this PR closed?
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Oh, that's why. Sorry for the noise. |
11 participants
replace_withinvokes a closure that will temporarily move out ofreference and later place back the value.
This is a part of a RFC. I'm closing it so it can be reopened later.