blob: 8383fcc164ba86bf2d604957404bb7f2d366de05 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
|
//! Types for controlling when drop is invoked.
use core::mem;
use core::mem::MaybeUninit;
/// A type to delay the drop handler invocation.
#[must_use = "to delay the drop handler invocation to the end of the scope"]
pub struct OnDrop<F: FnOnce()> {
f: MaybeUninit<F>,
}
impl<F: FnOnce()> OnDrop<F> {
/// Create a new instance.
pub fn new(f: F) -> Self {
Self { f: MaybeUninit::new(f) }
}
/// Prevent drop handler from running.
pub fn defuse(self) {
mem::forget(self)
}
}
impl<F: FnOnce()> Drop for OnDrop<F> {
fn drop(&mut self) {
unsafe { self.f.as_ptr().read()() }
}
}
/// An explosive ordinance that panics if it is improperly disposed of.
///
/// This is to forbid dropping futures, when there is absolutely no other choice.
///
/// To correctly dispose of this device, call the [defuse](struct.DropBomb.html#method.defuse)
/// method before this object is dropped.
#[must_use = "to delay the drop bomb invokation to the end of the scope"]
pub struct DropBomb {
_private: (),
}
impl DropBomb {
/// Create a new instance.
pub fn new() -> Self {
Self { _private: () }
}
/// Defuses the bomb, rendering it safe to drop.
pub fn defuse(self) {
mem::forget(self)
}
}
impl Drop for DropBomb {
fn drop(&mut self) {
panic!("boom")
}
}
|
