Struct gotham::state::State

pub struct State { /* fields omitted */ }

Provides storage for request state, and stores one item of each type. The types used for storage must implement the gotham::state::StateData trait to allow its storage. The gotham_derive crate provides a custom derive for StateData to make this more convenient.

Examples

extern crate gotham;
#[macro_use]
extern crate gotham_derive;

use gotham::state::State;

#[derive(StateData)]
struct MyStruct {
  value: i32
}

state.put(MyStruct { value: 1 });
assert_eq!(state.borrow::<MyStruct>().value, 1);

Methods

impl State

pub fn put<T>(&mut self, t: T) where
    T: StateData, 

Puts a value into the State storage. One value of each type is retained. Successive calls to put will overwrite the existing value of the same type.

Examples

state.put(MyStruct { value: 1 });
assert_eq!(state.borrow::<MyStruct>().value, 1);

state.put(AnotherStruct { value: "a string" });
state.put(MyStruct { value: 100 });

assert_eq!(state.borrow::<AnotherStruct>().value, "a string");
assert_eq!(state.borrow::<MyStruct>().value, 100);

pub fn has<T>(&self) -> bool where
    T: StateData, 

Determines if the current value exists in State storage.

Examples

state.put(MyStruct { value: 1 });
assert!(state.has::<MyStruct>());
assert_eq!(state.borrow::<MyStruct>().value, 1);

assert!(!state.has::<AnotherStruct>());

pub fn try_borrow<T>(&self) -> Option<&T> where
    T: StateData, 

Tries to borrow a value from the State storage.

Examples

state.put(MyStruct { value: 1 });
assert!(state.try_borrow::<MyStruct>().is_some());
assert_eq!(state.try_borrow::<MyStruct>().unwrap().value, 1);

assert!(state.try_borrow::<AnotherStruct>().is_none());

Important traits for &'a mut W

impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

pub fn borrow<T>(&self) -> &T where
    T: StateData, 

Borrows a value from the State storage.

Panics

If a value of type T is not present in State.

Examples

state.put(MyStruct { value: 1 });
assert_eq!(state.borrow::<MyStruct>().value, 1);

pub fn try_borrow_mut<T>(&mut self) -> Option<&mut T> where
    T: StateData, 

Tries to mutably borrow a value from the State storage.

Examples

state.put(MyStruct { value: 100 });

if let Some(a) = state.try_borrow_mut::<MyStruct>() {
    a.value += 10;
}

assert_eq!(state.borrow::<MyStruct>().value, 110);

assert!(state.try_borrow_mut::<AnotherStruct>().is_none());

Important traits for &'a mut W

impl<'a, W> Write for &'a mut W where
    W: Write + ?Sized, impl<'a, R> Read for &'a mut R where
    R: Read + ?Sized, impl<'a, I> Iterator for &'a mut I where
    I: Iterator + ?Sized,  type Item = <I as Iterator>::Item;

pub fn borrow_mut<T>(&mut self) -> &mut T where
    T: StateData, 

Mutably borrows a value from the State storage.

Panics

If a value of type T is not present in State.

Examples

state.put(MyStruct { value: 100 });

{
    let a = state.borrow_mut::<MyStruct>();
    a.value += 10;
}

assert_eq!(state.borrow::<MyStruct>().value, 110);

assert!(state.try_borrow_mut::<AnotherStruct>().is_none());

pub fn try_take<T>(&mut self) -> Option<T> where
    T: StateData, 

Tries to move a value out of the State storage and return ownership.

Examples

state.put(MyStruct { value: 110 });

assert_eq!(state.try_take::<MyStruct>().unwrap().value, 110);

assert!(state.try_take::<MyStruct>().is_none());
assert!(state.try_borrow_mut::<MyStruct>().is_none());
assert!(state.try_borrow::<MyStruct>().is_none());

assert!(state.try_take::<AnotherStruct>().is_none());

pub fn take<T>(&mut self) -> T where
    T: StateData, 

Moves a value out of the State storage and returns ownership.

Panics

If a value of type T is not present in State.

Examples

state.put(MyStruct { value: 110 });

assert_eq!(state.take::<MyStruct>().value, 110);

assert!(state.try_take::<MyStruct>().is_none());
assert!(state.try_borrow_mut::<MyStruct>().is_none());
assert!(state.try_borrow::<MyStruct>().is_none());

Trait Implementations