Trait std::any::Any
pub trait Any: 'static { fn type_id(&self) -> TypeId; }
A trait to emulate dynamic typing.
Most types implement Any
. However, any type which contains a non-'static
reference does not. See the module-level documentation for more details.
Required methods
fn type_id(&self) -> TypeId
Gets the TypeId
of self
.
Examples
use std::any::{Any, TypeId}; fn is_string(s: &dyn Any) -> bool { TypeId::of::<String>() == s.type_id() } assert_eq!(is_string(&0), false); assert_eq!(is_string(&"cookie monster".to_string()), true);
Implementations
impl dyn Any + 'static
Returns true
if the boxed type is the same as T
.
Examples
use std::any::Any; fn is_string(s: &dyn Any) { if s.is::<String>() { println!("It's a string!"); } else { println!("Not a string..."); } } is_string(&0); is_string(&"cookie monster".to_string());
Returns some reference to the boxed value if it is of type T
, or None
if it isn’t.
Examples
use std::any::Any; fn print_if_string(s: &dyn Any) { if let Some(string) = s.downcast_ref::<String>() { println!("It's a string({}): '{}'", string.len(), string); } else { println!("Not a string..."); } } print_if_string(&0); print_if_string(&"cookie monster".to_string());
Returns some mutable reference to the boxed value if it is of type T
, or None
if it isn’t.
Examples
use std::any::Any; fn modify_if_u32(s: &mut dyn Any) { if let Some(num) = s.downcast_mut::<u32>() { *num = 42; } } let mut x = 10u32; let mut s = "starlord".to_string(); modify_if_u32(&mut x); modify_if_u32(&mut s); assert_eq!(x, 42); assert_eq!(&s, "starlord");
impl dyn Any + Send + 'static
Forwards to the method defined on the type Any
.
Examples
use std::any::Any; fn is_string(s: &(dyn Any + Send)) { if s.is::<String>() { println!("It's a string!"); } else { println!("Not a string..."); } } is_string(&0); is_string(&"cookie monster".to_string());
Forwards to the method defined on the type Any
.
Examples
use std::any::Any; fn print_if_string(s: &(dyn Any + Send)) { if let Some(string) = s.downcast_ref::<String>() { println!("It's a string({}): '{}'", string.len(), string); } else { println!("Not a string..."); } } print_if_string(&0); print_if_string(&"cookie monster".to_string());
Forwards to the method defined on the type Any
.
Examples
use std::any::Any; fn modify_if_u32(s: &mut (dyn Any + Send)) { if let Some(num) = s.downcast_mut::<u32>() { *num = 42; } } let mut x = 10u32; let mut s = "starlord".to_string(); modify_if_u32(&mut x); modify_if_u32(&mut s); assert_eq!(x, 42); assert_eq!(&s, "starlord");
impl dyn Any + Sync + Send + 'static
Forwards to the method defined on the type Any
.
Examples
use std::any::Any; fn is_string(s: &(dyn Any + Send + Sync)) { if s.is::<String>() { println!("It's a string!"); } else { println!("Not a string..."); } } is_string(&0); is_string(&"cookie monster".to_string());
Forwards to the method defined on the type Any
.
Examples
use std::any::Any; fn print_if_string(s: &(dyn Any + Send + Sync)) { if let Some(string) = s.downcast_ref::<String>() { println!("It's a string({}): '{}'", string.len(), string); } else { println!("Not a string..."); } } print_if_string(&0); print_if_string(&"cookie monster".to_string());
Forwards to the method defined on the type Any
.
Examples
use std::any::Any; fn modify_if_u32(s: &mut (dyn Any + Send + Sync)) { if let Some(num) = s.downcast_mut::<u32>() { *num = 42; } } let mut x = 10u32; let mut s = "starlord".to_string(); modify_if_u32(&mut x); modify_if_u32(&mut s); assert_eq!(x, 42); assert_eq!(&s, "starlord");
Trait Implementations
impl Debug for dyn Any + Send + 'static
pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
Formats the value using the given formatter. Read more
impl Debug for dyn Any + Sync + Send + 'static
pub fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>
Formats the value using the given formatter. Read more
impl Debug for dyn Any + 'static
Implementors
© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/any/trait.Any.html