[−][src]Trait structural::field::rev_get_field::OptRevIntoField

pub trait OptRevIntoField<This>: RevIntoFieldImpl<This, Err = FailedAccess> { }

A trait alias for a fallible RevIntoFieldImpl, generally used to access fields inside enums.

This is the type we are accessing,and Self is a field path.

Example

This example shows how you can access an enum field by value.

use structural::field::OptRevIntoField;
use structural::for_examples::{StructFoo,WithBoom};
use structural::{StructuralExt,FP,fp};

let nope=StructFoo{ foo: WithBoom::Nope };
let boom=StructFoo{ foo: WithBoom::Boom{  a: "hello", b: &[3,5,8,13]  } };

assert_eq!( get_nested(nope), None );
assert_eq!( get_nested(boom), Some(&[3,5,8,13][..]) );

fn get_nested<T>(this:T)->Option<&'static [u16]>
where
    FP!(foo::Boom.b): OptRevIntoField<T,Ty=&'static [u16]>
{
    this.into_field(fp!(foo::Boom.b))
}

Implementors

impl<Path, This> OptRevIntoField<This> for Path where
    Path: RevIntoFieldImpl<This, Err = FailedAccess>, [src]

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