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Improve std::any module doc #34749

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Jul 12, 2016
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Improve std::any module doc #34749

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160 changes: 158 additions & 2 deletions src/libcore/any.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -92,6 +92,23 @@ use marker::{Reflect, Sized};
#[stable(feature = "rust1", since = "1.0.0")]
pub trait Any: Reflect + 'static {
/// Gets the `TypeId` of `self`.
///
/// # Examples
///
/// ```
/// #![feature(get_type_id)]
///
/// use std::any::{Any, TypeId};
///
/// fn is_string(s: &Any) -> bool {
/// TypeId::of::<String>() == s.get_type_id()
/// }
///
/// fn main() {
/// assert_eq!(is_string(&0), false);
/// assert_eq!(is_string(&"cookie monster".to_owned()), true);
/// }
/// ```
#[unstable(feature = "get_type_id",
reason = "this method will likely be replaced by an associated static",
issue = "27745")]
Expand Down Expand Up @@ -125,7 +142,26 @@ impl fmt::Debug for Any + Send {
}

impl Any {
/// Returns true if the boxed type is the same as `T`
/// Returns true if the boxed type is the same as `T`.
///
/// # Examples
///
/// ```
/// use std::any::Any;
///
/// fn is_string(s: &Any) {
/// if s.is::<String>() {
/// println!("It's a string!");
/// } else {
/// println!("Not a string...");
/// }
/// }
///
/// fn main() {
/// is_string(&0);
/// is_string(&"cookie monster".to_owned());
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn is<T: Any>(&self) -> bool {
Expand All @@ -141,6 +177,25 @@ impl Any {

/// 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: &Any) {
/// if let Some(string) = s.downcast_ref::<String>() {
/// println!("It's a string({}): '{}'", string.len(), string);
/// } else {
/// println!("Not a string...");
/// }
/// }
///
/// fn main() {
/// print_if_string(&0);
/// print_if_string(&"cookie monster".to_owned());
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
Expand All @@ -159,6 +214,29 @@ impl Any {

/// 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 Any) {
/// if let Some(num) = s.downcast_mut::<u32>() {
/// *num = 42;
/// }
/// }
///
/// fn main() {
/// let mut x = 10u32;
/// let mut s = "starlord".to_owned();
///
/// modify_if_u32(&mut x);
/// modify_if_u32(&mut s);
///
/// assert_eq!(x, 42);
/// assert_eq!(&s, "starlord");
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
Expand All @@ -178,20 +256,81 @@ impl Any {

impl Any+Send {
/// Forwards to the method defined on the type `Any`.
///
/// # Examples
///
/// ```
/// use std::any::Any;
///
/// fn is_string(s: &(Any + Send)) {
/// if s.is::<String>() {
/// println!("It's a string!");
/// } else {
/// println!("Not a string...");
/// }
/// }
///
/// fn main() {
/// is_string(&0);
/// is_string(&"cookie monster".to_owned());
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn is<T: Any>(&self) -> bool {
Any::is::<T>(self)
}

/// Forwards to the method defined on the type `Any`.
///
/// # Examples
///
/// ```
/// use std::any::Any;
///
/// fn print_if_string(s: &(Any + Send)) {
/// if let Some(string) = s.downcast_ref::<String>() {
/// println!("It's a string({}): '{}'", string.len(), string);
/// } else {
/// println!("Not a string...");
/// }
/// }
///
/// fn main() {
/// print_if_string(&0);
/// print_if_string(&"cookie monster".to_owned());
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn downcast_ref<T: Any>(&self) -> Option<&T> {
Any::downcast_ref::<T>(self)
}

/// Forwards to the method defined on the type `Any`.
///
/// # Examples
///
/// ```
/// use std::any::Any;
///
/// fn modify_if_u32(s: &mut (Any+ Send)) {
/// if let Some(num) = s.downcast_mut::<u32>() {
/// *num = 42;
/// }
/// }
///
/// fn main() {
/// let mut x = 10u32;
/// let mut s = "starlord".to_owned();
///
/// modify_if_u32(&mut x);
/// modify_if_u32(&mut s);
///
/// assert_eq!(x, 42);
/// assert_eq!(&s, "starlord");
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn downcast_mut<T: Any>(&mut self) -> Option<&mut T> {
Expand Down Expand Up @@ -220,7 +359,24 @@ pub struct TypeId {

impl TypeId {
/// Returns the `TypeId` of the type this generic function has been
/// instantiated with
/// instantiated with.
///
/// # Examples
///
/// ```
/// #![feature(get_type_id)]
///
/// use std::any::{Any, TypeId};
///
/// fn is_string(s: &Any) -> bool {
/// TypeId::of::<String>() == s.get_type_id()
/// }
///
/// fn main() {
/// assert_eq!(is_string(&0), false);
/// assert_eq!(is_string(&"cookie monster".to_owned()), true);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn of<T: ?Sized + Reflect + 'static>() -> TypeId {
TypeId {
Expand Down