Function tracing_core::stdlib::any::type_name_of_val
1.76.0 (const: unstable) · source · pub fn type_name_of_val<T>(_val: &T) -> &'static strwhere
T: ?Sized,
Expand description
Returns the type name of the pointed-to value as a string slice.
This is the same as type_name::<T>()
, but can be used where the type of a
variable is not easily available.
§Note
Like type_name
, this is intended for diagnostic use and the exact output is not
guaranteed. It provides a best-effort description, but the output may change between
versions of the compiler.
In short: use this for debugging, avoid using the output to affect program behavior. More
information is available at type_name
.
Additionally, this function does not resolve trait objects. This means that
type_name_of_val(&7u32 as &dyn Debug)
may return "dyn Debug"
, but will not return "u32"
at this time.
§Examples
Prints the default integer and float types.
use std::any::type_name_of_val;
let s = "foo";
let x: i32 = 1;
let y: f32 = 1.0;
assert!(type_name_of_val(&s).contains("str"));
assert!(type_name_of_val(&x).contains("i32"));
assert!(type_name_of_val(&y).contains("f32"));