1.9.0[−][src]Struct std::panic::AssertUnwindSafe
A simple wrapper around a type to assert that it is unwind safe.
When using catch_unwind
it may be the case that some of the closed over
variables are not unwind safe. For example if &mut T
is captured the
compiler will generate a warning indicating that it is not unwind safe. It
may not be the case, however, that this is actually a problem due to the
specific usage of catch_unwind
if unwind safety is specifically taken into
account. This wrapper struct is useful for a quick and lightweight
annotation that a variable is indeed unwind safe.
Examples
One way to use AssertUnwindSafe
is to assert that the entire closure
itself is unwind safe, bypassing all checks for all variables:
use std::panic::{self, AssertUnwindSafe}; let mut variable = 4; // This code will not compile because the closure captures `&mut variable` // which is not considered unwind safe by default. // panic::catch_unwind(|| { // variable += 3; // }); // This, however, will compile due to the `AssertUnwindSafe` wrapper let result = panic::catch_unwind(AssertUnwindSafe(|| { variable += 3; })); // ...Run
Wrapping the entire closure amounts to a blanket assertion that all captured variables are unwind safe. This has the downside that if new captures are added in the future, they will also be considered unwind safe. Therefore, you may prefer to just wrap individual captures, as shown below. This is more annotation, but it ensures that if a new capture is added which is not unwind safe, you will get a compilation error at that time, which will allow you to consider whether that new capture in fact represent a bug or not.
use std::panic::{self, AssertUnwindSafe}; let mut variable = 4; let other_capture = 3; let result = { let mut wrapper = AssertUnwindSafe(&mut variable); panic::catch_unwind(move || { **wrapper += other_capture; }) }; // ...Run
Trait Implementations
impl<T> UnwindSafe for AssertUnwindSafe<T>
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impl<T> UnwindSafe for AssertUnwindSafe<T>
impl<T> RefUnwindSafe for AssertUnwindSafe<T>
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impl<T> RefUnwindSafe for AssertUnwindSafe<T>
impl<T: Debug> Debug for AssertUnwindSafe<T>
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impl<T: Debug> Debug for AssertUnwindSafe<T>
impl<T> Deref for AssertUnwindSafe<T>
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impl<T> Deref for AssertUnwindSafe<T>
impl<T> DerefMut for AssertUnwindSafe<T>
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impl<T> DerefMut for AssertUnwindSafe<T>
impl<R, F: FnOnce() -> R> FnOnce() for AssertUnwindSafe<F>
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impl<R, F: FnOnce() -> R> FnOnce() for AssertUnwindSafe<F>
impl<'a, F: Future> Future for AssertUnwindSafe<F>
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impl<'a, F: Future> Future for AssertUnwindSafe<F>
Auto Trait Implementations
impl<T> Send for AssertUnwindSafe<T> where
T: Send,
impl<T> Send for AssertUnwindSafe<T> where
T: Send,
impl<T> Sync for AssertUnwindSafe<T> where
T: Sync,
impl<T> Sync for AssertUnwindSafe<T> where
T: Sync,
Blanket Implementations
impl<T, U> TryFrom for T where
T: From<U>,
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impl<T, U> TryFrom for T where
T: From<U>,
type Error = !
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
Performs the conversion.
impl<T> From for T
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impl<T> From for T
impl<T, U> TryInto for T where
U: TryFrom<T>,
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impl<T, U> TryInto for T where
U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
Performs the conversion.
impl<T, U> Into for T where
U: From<T>,
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impl<T, U> Into for T where
U: From<T>,
impl<T> Borrow for T where
T: ?Sized,
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impl<T> Borrow for T where
T: ?Sized,
ⓘImportant traits for &'a mut Ifn borrow(&self) -> &T
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fn borrow(&self) -> &T
Immutably borrows from an owned value. Read more
impl<T> BorrowMut for T where
T: ?Sized,
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impl<T> BorrowMut for T where
T: ?Sized,
ⓘImportant traits for &'a mut Ifn borrow_mut(&mut self) -> &mut T
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fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
impl<T> Any for T where
T: 'static + ?Sized,
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impl<T> Any for T where
T: 'static + ?Sized,
fn get_type_id(&self) -> TypeId
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fn get_type_id(&self) -> TypeId
🔬 This is a nightly-only experimental API. (get_type_id
#27745)
this method will likely be replaced by an associated static
Gets the TypeId
of self
. Read more
impl<A, F> FnBox for F where
F: FnOnce<A>,
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impl<A, F> FnBox for F where
F: FnOnce<A>,
type Output = <F as FnOnce<A>>::Output
🔬 This is a nightly-only experimental API. (fnbox
#28796)
will be deprecated if and when Box<FnOnce>
becomes usable
fn call_box(self: Box<F>, args: A) -> <F as FnOnce<A>>::Output
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fn call_box(self: Box<F>, args: A) -> <F as FnOnce<A>>::Output
🔬 This is a nightly-only experimental API. (fnbox
#28796)
will be deprecated if and when Box<FnOnce>
becomes usable