pub trait HasGetter<S, A> {
type GetterError;
// Required method
fn try_get(&self, source: &S) -> Result<A, Self::GetterError>;
}Expand description
A base trait for optics that provides a partial getter operation.
This trait defines the ability to retrieve a value of type A from a source of type S,
potentially failing with an error of type GetterError. It serves as a foundational trait for
constructing more complex optics like lenses and prisms.
§Associated Types
GetterError: The type of the error that may occur during retrieval. This will propagete as the error type of retrieval of concrete optics that implement this trait.
§Notes
- Currently, you will likely need to Clone or Copy the result in order to extract it from the source.
§Implementors
Types that implement HasPartialGetter can be used to define optics that allow for
partial retrieval of values from a source, where the retrieval may fail.
- [
PartialGetter] — optic that allows only fallible read operations - [
Getter] — optic that allows only infallible read operations - [
Prism] — optic that allows for fallible retrieval of values. - [
Lens] — optic that allows for infallible retrieval of values. - [
FallibleIso] — reversible optic that can allows for fallible conversion of values in both directions. - [
Iso] — reversible optic that never fails.
Required Associated Types§
Sourcetype GetterError
type GetterError
The type of error that may occur during retrieval. Use Infallible for infallible optics.
Required Methods§
Sourcefn try_get(&self, source: &S) -> Result<A, Self::GetterError>
fn try_get(&self, source: &S) -> Result<A, Self::GetterError>
Attempts to retrieve a value of type A from a source of type S.
§Parameters
source: A reference to the source of typeSfrom which the value is to be retrieved.
§Errors
It returns an error specified by the implementing optic if the focus fails.
§Returns
Returns a Result<A, Self::GetterError>, of the value the optic focuses on.