pub struct ConstantExpression { /* private fields */ }
Expand description

A constant value in a Expression.

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impl ConstantExpression

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

Return the inner pointer to the underlying C value.

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pub unsafe fn from_glib_ptr_borrow<'a>( ptr: *const *const GtkConstantExpression ) -> &'a Self

Borrows the underlying C value.

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impl ConstantExpression

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pub fn for_value(value: &Value) -> ConstantExpression

Creates an expression that always evaluates to the given value.

§value

a GValue

§Returns

a new Expression

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pub fn value(&self) -> Value

Gets the value that a constant expression evaluates to.

§Returns

the value

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impl ConstantExpression

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pub fn upcast(self) -> Expression

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pub fn upcast_ref(&self) -> &Expression

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impl ConstantExpression

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pub fn new(value: impl Into<Value>) -> Self

Creates a Expression that evaluates to the object given by the arguments.

§value_type

The type of the object

§Returns

a new Expression

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pub fn value_as<V: for<'b> FromValue<'b> + 'static>(&self) -> V

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

Methods from Deref<Target = Expression>§

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

Return the inner pointer to the underlying C value.

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pub const NONE: Option<&'static Expression> = None

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

Bind target’s property named property to self.

The value that self evaluates to is set via g_object_set() on target. This is repeated whenever self changes to ensure that the object’s property stays synchronized with self.

If self’s evaluation fails, target’s property is not updated. You can ensure that this doesn’t happen by using a fallback expression.

Note that this function takes ownership of self. If you want to keep it around, you should Gtk::Expression::ref() it beforehand.

§target

the target object to bind to

§property

name of the property on target to bind to

§this_

the this argument for the evaluation of self

§Returns

a ExpressionWatch

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pub fn value_type(&self) -> Type

Gets the GType that this expression evaluates to.

This type is constant and will not change over the lifetime of this expression.

§Returns

The type returned from evaluate()

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pub fn is_static(&self) -> bool

Checks if the expression is static.

A static expression will never change its result when evaluate() is called on it with the same arguments.

That means a call to watch() is not necessary because it will never trigger a notify.

§Returns

TRUE if the expression is static

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

Watch the given expression for changes.

The @notify function will be called whenever the evaluation of self may have changed.

GTK cannot guarantee that the evaluation did indeed change when the @notify gets invoked, but it guarantees the opposite: When it did in fact change, the @notify will be invoked.

§this_

the this argument to watch

§notify

callback to invoke when the expression changes

§Returns

The newly installed watch. Note that the only reference held to the watch will be released when the watch is unwatched which can happen automatically, and not just via ExpressionWatch::unwatch(). You should call Gtk::ExpressionWatch::ref() if you want to keep the watch around.

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pub fn upcast_ref(&self) -> &Self

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

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

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pub fn type_(&self) -> Type

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

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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.

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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.

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

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");
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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§

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impl AsRef<Expression> for ConstantExpression

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fn as_ref(&self) -> &Expression

Converts this type into a shared reference of the (usually inferred) input type.
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impl Clone for ConstantExpression

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fn clone(&self) -> Self

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for ConstantExpression

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

Formats the value using the given formatter. Read more
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impl Deref for ConstantExpression

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type Target = Expression

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.
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impl From<ConstantExpression> for Value

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fn from(e: ConstantExpression) -> Self

Converts to this type from the input type.
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impl<'a> FromValue<'a> for ConstantExpression

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type Checker = GenericValueTypeOrNoneChecker<ConstantExpression>

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

Get the contained value from a Value. Read more
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impl HasParamSpec for ConstantExpression

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type ParamSpec = ParamSpecExpression

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type SetValue = ConstantExpression

Preferred value to be used as setter for the associated ParamSpec.
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type BuilderFn = for<'a> fn(_: &'a str) -> ParamSpecExpressionBuilder<'a>

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fn param_spec_builder() -> Self::BuilderFn

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impl StaticType for ConstantExpression

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fn static_type() -> Type

Returns the type identifier of Self.
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impl ToValue for ConstantExpression

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fn to_value(&self) -> Value

Convert a value to a Value.
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fn value_type(&self) -> Type

Returns the type identifier of self. Read more
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impl ToValueOptional for ConstantExpression

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

Convert an Option to a Value.
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impl ValueType for ConstantExpression

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type Type = ConstantExpression

Type to get the Type from. Read more
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impl IsExpression for ConstantExpression

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GList> for T

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unsafe fn from_glib_none_num_as_vec(ptr: *const GList, num: usize) -> Vec<T>

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unsafe fn from_glib_container_num_as_vec(_: *const GList, _: usize) -> Vec<T>

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unsafe fn from_glib_full_num_as_vec(_: *const GList, _: usize) -> Vec<T>

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GPtrArray> for T

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unsafe fn from_glib_none_num_as_vec(ptr: *const GPtrArray, num: usize) -> Vec<T>

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unsafe fn from_glib_container_num_as_vec( _: *const GPtrArray, _: usize ) -> Vec<T>

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unsafe fn from_glib_full_num_as_vec(_: *const GPtrArray, _: usize) -> Vec<T>

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GSList> for T

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unsafe fn from_glib_none_num_as_vec(ptr: *const GSList, num: usize) -> Vec<T>

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unsafe fn from_glib_container_num_as_vec(_: *const GSList, _: usize) -> Vec<T>

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unsafe fn from_glib_full_num_as_vec(_: *const GSList, _: usize) -> Vec<T>

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GList> for T

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unsafe fn from_glib_none_num_as_vec(ptr: *mut GList, num: usize) -> Vec<T>

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unsafe fn from_glib_container_num_as_vec(ptr: *mut GList, num: usize) -> Vec<T>

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unsafe fn from_glib_full_num_as_vec(ptr: *mut GList, num: usize) -> Vec<T>

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GPtrArray> for T

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unsafe fn from_glib_none_num_as_vec(ptr: *mut GPtrArray, num: usize) -> Vec<T>

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unsafe fn from_glib_container_num_as_vec( ptr: *mut GPtrArray, num: usize ) -> Vec<T>

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unsafe fn from_glib_full_num_as_vec(ptr: *mut GPtrArray, num: usize) -> Vec<T>

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GSList> for T

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unsafe fn from_glib_none_num_as_vec(ptr: *mut GSList, num: usize) -> Vec<T>

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unsafe fn from_glib_container_num_as_vec(ptr: *mut GSList, num: usize) -> Vec<T>

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unsafe fn from_glib_full_num_as_vec(ptr: *mut GSList, num: usize) -> Vec<T>

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GList> for T

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unsafe fn from_glib_none_as_vec(ptr: *const GList) -> Vec<T>

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unsafe fn from_glib_container_as_vec(_: *const GList) -> Vec<T>

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unsafe fn from_glib_full_as_vec(_: *const GList) -> Vec<T>

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GPtrArray> for T

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unsafe fn from_glib_none_as_vec(ptr: *const GPtrArray) -> Vec<T>

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unsafe fn from_glib_container_as_vec(_: *const GPtrArray) -> Vec<T>

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unsafe fn from_glib_full_as_vec(_: *const GPtrArray) -> Vec<T>

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GSList> for T

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unsafe fn from_glib_none_as_vec(ptr: *const GSList) -> Vec<T>

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unsafe fn from_glib_container_as_vec(_: *const GSList) -> Vec<T>

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unsafe fn from_glib_full_as_vec(_: *const GSList) -> Vec<T>

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GList> for T

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unsafe fn from_glib_none_as_vec(ptr: *mut GList) -> Vec<T>

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unsafe fn from_glib_container_as_vec(ptr: *mut GList) -> Vec<T>

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unsafe fn from_glib_full_as_vec(ptr: *mut GList) -> Vec<T>

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GPtrArray> for T

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unsafe fn from_glib_none_as_vec(ptr: *mut GPtrArray) -> Vec<T>

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unsafe fn from_glib_container_as_vec(ptr: *mut GPtrArray) -> Vec<T>

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unsafe fn from_glib_full_as_vec(ptr: *mut GPtrArray) -> Vec<T>

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GSList> for T

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unsafe fn from_glib_none_as_vec(ptr: *mut GSList) -> Vec<T>

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unsafe fn from_glib_container_as_vec(ptr: *mut GSList) -> Vec<T>

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unsafe fn from_glib_full_as_vec(ptr: *mut GSList) -> Vec<T>

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoClosureReturnValue for T
where T: Into<Value>,

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impl<T> Property for T
where T: HasParamSpec,

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type Value = T

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impl<T> PropertyGet for T
where T: HasParamSpec,

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type Value = T

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fn get<R, F>(&self, f: F) -> R
where F: Fn(&<T as PropertyGet>::Value) -> R,

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impl<T> StaticTypeExt for T
where T: StaticType,

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fn ensure_type()

Ensures that the type has been registered with the type system.
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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T> TransparentType for T

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T> TryFromClosureReturnValue for T
where T: for<'a> FromValue<'a> + StaticType + 'static,

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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<'a, T, C, E> FromValueOptional<'a> for T
where T: FromValue<'a, Checker = C>, C: ValueTypeChecker<Error = ValueTypeMismatchOrNoneError<E>>, E: Error + Send + 'static,