Struct gtk4::Expression

#[repr(transparent)]
pub struct Expression { /* private fields */ }

Implementations

impl Expression

pub const NONE: Option<&'static Expression>

pub fn bind(
    &self,
    target: &impl IsA<Object>,
    property: &str,
    this_: Option<&impl IsA<Object>>
) -> ExpressionWatch

pub fn value_type(&self) -> Type

pub fn is_static(&self) -> bool

pub fn watch<P: Fn() + 'static>(
    &self,
    this_: Option<&impl IsA<Object>>,
    notify: P
) -> ExpressionWatch

impl Expression

pub fn is<E: IsExpression>(&self) -> bool

pub fn downcast<E: IsExpression>(self) -> Result<E, Expression>

pub fn downcast_ref<E: IsExpression>(&self) -> Option<&E>

pub fn type_(&self) -> Type

pub fn evaluate(&self, this: Option<&impl IsA<Object>>) -> Option<Value>

pub fn evaluate_as<V: for<'b> FromValue<'b> + 'static, T: IsA<Object>>(
    &self,
    this: Option<&T>
) -> Option<V>

Similar to Self::evaluate but panics if the value is of a different type.

pub fn chain_property<T: IsA<Object>>(
    &self,
    property_name: &str
) -> PropertyExpression

Create a PropertyExpression that looks up for property_name with self as parameter. This is useful in long chains of Expressions.

pub fn chain_closure<R>(&self, closure: RustClosure) -> ClosureExpression where
    R: ValueType, 

Create a ClosureExpression from a glib::Closure with self as the second parameter and R as the return type. The return type is checked at run-time and must always be specified. This is useful in long chains of Expressions when using the glib::closure! macro.

Note that the first parameter will always be the this object bound to the expression. If None is passed as this then the type of the first parameter must be Option<glib::Object> otherwise type checking will panic.

use gtk::prelude::*;
use gtk::glib;
use glib::{closure, Object};

let button = gtk::Button::new();
button.set_label("Hello");
let label = button
    .property_expression("label")
    .chain_closure::<String>(closure!(|_: Option<Object>, label: &str| {
        format!("{} World", label)
    }))
    .evaluate_as::<String, _>(gtk::Widget::NONE);
assert_eq!(label.unwrap(), "Hello World");

pub fn chain_closure_with_callback<F, R>(&self, f: F) -> ClosureExpression where
    F: Fn(&[Value]) -> R + 'static,
    R: ValueType, 

Create a ClosureExpression with self as the second parameter. This is useful in long chains of Expressions.

Trait Implementations

impl AsRef<Expression> for ClosureExpression

fn as_ref(&self) -> &Expression

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<Expression> for ConstantExpression

fn as_ref(&self) -> &Expression

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<Expression> for ObjectExpression

fn as_ref(&self) -> &Expression

Converts this type into a shared reference of the (usually inferred) input type.

impl AsRef<Expression> for PropertyExpression

fn as_ref(&self) -> &Expression

Converts this type into a shared reference of the (usually inferred) input type.

impl Clone for Expression

fn clone(&self) -> Self

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Expression

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for Expression

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'a> FromValue<'a> for Expression

type Checker = GenericValueTypeOrNoneChecker<Self>

Value type checker.

unsafe fn from_value(value: &'a Value) -> Self

Get the contained value from a Value.

impl StaticType for Expression

fn static_type() -> Type

Returns the type identifier of Self.

impl ToValue for Expression

fn to_value(&self) -> Value

Convert a value to a Value.

fn value_type(&self) -> Type

Returns the type identifer of self.

impl ToValueOptional for Expression

fn to_value_optional(s: Option<&Self>) -> Value

Convert an Option to a Value.

impl ValueType for Expression

type Type = Self

Type to get the Type from.