Struct gtk4::ObjectExpression

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#[repr(transparent)]
pub struct ObjectExpression { /* private fields */ }
Expand description

A GObject value in a Expression.

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impl ObjectExpression

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pub fn new(object: &impl IsA<Object>) -> ObjectExpression

Creates an expression evaluating to the given object with a weak reference.

Once the object is disposed, it will fail to evaluate.

This expression is meant to break reference cycles.

If you want to keep a reference to object, use ConstantExpression::new().

object

object to watch

Returns

a new Expression

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pub fn object(&self) -> Option<Object>

Gets the object that the expression evaluates to.

Returns

the object, or NULL

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impl ObjectExpression

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pub fn upcast(self) -> Expression

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pub fn upcast_ref(&self) -> &Expression

Methods from Deref<Target = Expression>§

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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 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) -> ClosureExpressionwhere 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");
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pub fn chain_closure_with_callback<F, R>(&self, f: F) -> ClosureExpressionwhere 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 ObjectExpression

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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 ObjectExpression

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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 ObjectExpression

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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 ObjectExpression

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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 Display for ObjectExpression

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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<'a> FromValue<'a> for ObjectExpression

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type Checker = GenericValueTypeOrNoneChecker<ObjectExpression>

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 StaticType for ObjectExpression

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fn static_type() -> Type

Returns the type identifier of Self.
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impl ToValue for ObjectExpression

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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 identifer of self. Read more
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impl ToValueOptional for ObjectExpression

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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 ObjectExpression

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type Type = ObjectExpression

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

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for Twhere 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 Twhere T: ?Sized,

const: unstable · source§

fn borrow(&self) -> &T

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

const: unstable · source§

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 Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GPtrArray> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GSList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GPtrArray> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GSList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GPtrArray> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *const GSList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GPtrArray> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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impl<T> FromGlibPtrArrayContainerAsVec<<T as GlibPtrDefault>::GlibType, *mut GSList> for Twhere T: GlibPtrDefault + FromGlibPtrNone<<T as GlibPtrDefault>::GlibType> + FromGlibPtrFull<<T as GlibPtrDefault>::GlibType>,

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

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

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

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

const: unstable · source§

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> StaticTypeExt for Twhere 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> ToClosureReturnValue for Twhere T: ToValue,

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impl<T> ToOwned for Twhere 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> ToString for Twhere T: Display + ?Sized,

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default fn to_string(&self) -> String

Converts the given value to a String. Read more
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impl<T, U> TryFrom<U> for Twhere U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
const: unstable · source§

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

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

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

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

The type returned in the event of a conversion error.
const: unstable · source§

fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<'a, T, C> FromValueOptional<'a> for Twhere T: FromValue<'a, Checker = C>, C: ValueTypeChecker<Error = ValueTypeMismatchOrNoneError>,