Struct LazyUi

pub struct LazyUi<T> {
    pub ui: RefCell<T>,
    pub latest_parent: Cell<Option<ControlHandle>>,
    pub is_built: Cell<bool>,
}

Implements PartialUi and delegates to a PartialUi inside a RefCell.

Note: if this is located inside a PartialUI then any parent passed to that partial UI won’t be passed down one step more to this type, and so the initial parent will be set to None.

Fields

ui: RefCell<T>

latest_parent: Cell<Option<ControlHandle>>

is_built: Cell<bool>

Implementations

impl<T> LazyUi<T>

pub fn clear(&self)

where T: Default,

Reset the wrapped UI to its default state.

pub fn build_with_latest_parent(&self) -> Result<(), NwgError>

where T: LazyUiHooks + PartialUi,

Build the UI with the most recently used parent. Make sure the UI isn’t already constructed when calling this method, perhaps by calling clear first.

pub fn build(&self, parent: Option<ControlHandle>) -> Result<(), NwgError>

where T: LazyUiHooks + PartialUi,

Build the UI with the given parent. Make sure the UI isn’t already constructed when calling this method, perhaps by calling clear first.

Methods from Deref<Target = RefCell<T>>

pub fn replace(&self, t: T) -> T

Replaces the wrapped value with a new one, returning the old value, without deinitializing either one.

This function corresponds to std::mem::replace.

Panics

Panics if the value is currently borrowed.

Examples

use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace(6);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));

pub fn replace_with<F>(&self, f: F) -> T

where F: FnOnce(&mut T) -> T,

Replaces the wrapped value with a new one computed from f, returning the old value, without deinitializing either one.

Panics

Panics if the value is currently borrowed.

Examples

use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace_with(|&mut old| old + 1);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));

pub fn swap(&self, other: &RefCell<T>)

Swaps the wrapped value of self with the wrapped value of other, without deinitializing either one.

This function corresponds to std::mem::swap.

Panics

Panics if the value in either RefCell is currently borrowed, or if self and other point to the same RefCell.

Examples

use std::cell::RefCell;
let c = RefCell::new(5);
let d = RefCell::new(6);
c.swap(&d);
assert_eq!(c, RefCell::new(6));
assert_eq!(d, RefCell::new(5));

pub fn borrow(&self) -> Ref<'_, T>

Immutably borrows the wrapped value.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

Panics

Panics if the value is currently mutably borrowed. For a non-panicking variant, use try_borrow.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let borrowed_five = c.borrow();
let borrowed_five2 = c.borrow();

An example of panic:

use std::cell::RefCell;

let c = RefCell::new(5);

let m = c.borrow_mut();
let b = c.borrow(); // this causes a panic

pub fn try_borrow(&self) -> Result<Ref<'_, T>, BorrowError>

Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

This is the non-panicking variant of borrow.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(c.try_borrow().is_err());
}

{
    let m = c.borrow();
    assert!(c.try_borrow().is_ok());
}

pub fn borrow_mut(&self) -> RefMut<'_, T>

Mutably borrows the wrapped value.

The borrow lasts until the returned RefMut or all RefMuts derived from it exit scope. The value cannot be borrowed while this borrow is active.

Panics

Panics if the value is currently borrowed. For a non-panicking variant, use try_borrow_mut.

Examples

use std::cell::RefCell;

let c = RefCell::new("hello".to_owned());

*c.borrow_mut() = "bonjour".to_owned();

assert_eq!(&*c.borrow(), "bonjour");

An example of panic:

use std::cell::RefCell;

let c = RefCell::new(5);
let m = c.borrow();

let b = c.borrow_mut(); // this causes a panic

pub fn try_borrow_mut(&self) -> Result<RefMut<'_, T>, BorrowMutError>

Mutably borrows the wrapped value, returning an error if the value is currently borrowed.

The borrow lasts until the returned RefMut or all RefMuts derived from it exit scope. The value cannot be borrowed while this borrow is active.

This is the non-panicking variant of borrow_mut.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow();
    assert!(c.try_borrow_mut().is_err());
}

assert!(c.try_borrow_mut().is_ok());

pub fn as_ptr(&self) -> *mut T

Returns a raw pointer to the underlying data in this cell.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

let ptr = c.as_ptr();

pub fn get_mut(&mut self) -> &mut T

Returns a mutable reference to the underlying data.

Since this method borrows RefCell mutably, it is statically guaranteed that no borrows to the underlying data exist. The dynamic checks inherent in borrow_mut and most other methods of RefCell are therefore unnecessary. Note that this method does not reset the borrowing state if borrows were previously leaked (e.g., via forget() on a Ref or RefMut). For that purpose, consider using the unstable undo_leak method.

This method can only be called if RefCell can be mutably borrowed, which in general is only the case directly after the RefCell has been created. In these situations, skipping the aforementioned dynamic borrowing checks may yield better ergonomics and runtime-performance.

In most situations where RefCell is used, it can’t be borrowed mutably. Use borrow_mut to get mutable access to the underlying data then.

Examples

use std::cell::RefCell;

let mut c = RefCell::new(5);
*c.get_mut() += 1;

assert_eq!(c, RefCell::new(6));

pub fn undo_leak(&mut self) -> &mut T

🔬This is a nightly-only experimental API. (cell_leak)

Undo the effect of leaked guards on the borrow state of the RefCell.

This call is similar to get_mut but more specialized. It borrows RefCell mutably to ensure no borrows exist and then resets the state tracking shared borrows. This is relevant if some Ref or RefMut borrows have been leaked.

Examples

#![feature(cell_leak)]
use std::cell::RefCell;

let mut c = RefCell::new(0);
std::mem::forget(c.borrow_mut());

assert!(c.try_borrow().is_err());
c.undo_leak();
assert!(c.try_borrow().is_ok());

pub unsafe fn try_borrow_unguarded(&self) -> Result<&T, BorrowError>

Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

Safety

Unlike RefCell::borrow, this method is unsafe because it does not return a Ref, thus leaving the borrow flag untouched. Mutably borrowing the RefCell while the reference returned by this method is alive is undefined behavior.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(unsafe { c.try_borrow_unguarded() }.is_err());
}

{
    let m = c.borrow();
    assert!(unsafe { c.try_borrow_unguarded() }.is_ok());
}

pub fn take(&self) -> T

Takes the wrapped value, leaving Default::default() in its place.

Panics

Panics if the value is currently borrowed.

Examples

use std::cell::RefCell;

let c = RefCell::new(5);
let five = c.take();

assert_eq!(five, 5);
assert_eq!(c.into_inner(), 0);

Trait Implementations

impl<T: Default> Default for LazyUi<T>

fn default() -> LazyUi<T>

Returns the “default value” for a type.

impl<T> Deref for LazyUi<T>

type Target = RefCell<T>

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for LazyUi<T>

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T> PartialUi for LazyUi<T>

where T: LazyUiHooks + PartialUi,

fn build_partial<W: Into<ControlHandle>>( data: &mut Self, parent: Option<W>, ) -> Result<(), NwgError>

Should initialize the GUI components. Similar to NativeUi::build_ui except it doesn’t handle event binding.

fn process_event(&self, evt: Event, evt_data: &EventData, handle: ControlHandle)

Should process the events of the partial. This method will probably be called from an event handler bound in the parent GUI structure.

fn handles(&self) -> Vec<&ControlHandle>

Should return the handles of the top level parent controls (such as Windows). Those handle should be used to bind the default events handler.