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assert_no_alloc

nice_assert_no_alloc

Function assert_no_alloc 

Source 
pub fn assert_no_alloc<T, F: FnOnce() -> T>(func: F) -> T
Expand description

Calls the func closure, but forbids any (de)allocations.

If a call to the allocator is made, the program will abort with an error, print a warning (depending on the warn_debug feature flag. Or ignore the situation, when compiled in --release mode with the disable_release feature flag set (which is the default)).

Examples found in repository?
examples/main.rs (lines 14-26)
7fn main() {
8    println!("Alloc is allowed. Let's allocate some memory...");
9    let mut vec_can_push = Vec::new();
10    vec_can_push.push(42);
11
12    println!();
13
14    let fib5 = assert_no_alloc(|| {
15        println!("Alloc is forbidden. Let's calculate something without memory allocations...");
16
17        fn fib(n: u32) -> u32 {
18            if n <= 1 {
19                1
20            } else {
21                fib(n - 1) + fib(n - 2)
22            }
23        }
24
25        fib(5)
26    });
27    println!("\tSuccess, the 5th fibonacci number is {}", fib5);
28    println!();
29
30    assert_no_alloc(|| {
31        println!("Alloc is forbidden. Let's allocate some memory...");
32        let mut vec_cannot_push = Vec::new();
33        vec_cannot_push.push(42); // panics
34    });
35
36    println!("This will not be executed if the above allocation has aborted.");
37}