Trait frunk_core::labelled::LabelledGeneric

pub trait LabelledGeneric {
    type Repr;

    // Required methods
    fn into(self) -> Self::Repr;
    fn from(repr: Self::Repr) -> Self;

    // Provided methods
    fn convert_from<Src>(src: Src) -> Self
       where Src: LabelledGeneric<Repr = Self::Repr>,
             Self: Sized { ... }
    fn sculpted_convert_from<A, Indices>(a: A) -> Self
       where A: LabelledGeneric,
             Self: Sized,
             <A as LabelledGeneric>::Repr: Sculptor<<Self as LabelledGeneric>::Repr, Indices> { ... }
    fn transform_from<Src, Indices>(src: Src) -> Self
       where Src: LabelledGeneric,
             Self: Sized,
             <Src as LabelledGeneric>::Repr: Sculptor<<Self as LabelledGeneric>::Repr, Indices> { ... }
}

A trait that converts from a type to a labelled generic representation.

LabelledGenerics allow us to have completely type-safe, boilerplate free conversions between different structs.

For the most part, you should be using the derivation that is available through frunk_derive to generate instances of this trait for your types.

Examples

use frunk::LabelledGeneric;

#[derive(LabelledGeneric)]
struct NewUser<'a> {
    first_name: &'a str,
    last_name: &'a str,
    age: usize,
}

// Notice that the fields are mismatched in terms of ordering
#[derive(LabelledGeneric)]
struct SavedUser<'a> {
    last_name: &'a str,
    age: usize,
    first_name: &'a str,
}

let n_user = NewUser {
    first_name: "Joe",
    last_name: "Blow",
    age: 30,
};

// transform_from automagically sculpts the labelled generic
// representation of the source object to that of the target type
let s_user: SavedUser = frunk::transform_from(n_user); // done

Required Associated Types

type Repr

The labelled generic representation type.

Required Methods

fn into(self) -> Self::Repr

Convert a value to its representation type Repr.

fn from(repr: Self::Repr) -> Self

Convert a value’s labelled representation type Repr to the values’s type.

Provided Methods

fn convert_from<Src>(src: Src) -> Self

where Src: LabelledGeneric<Repr = Self::Repr>, Self: Sized,

Convert from one type to another using a type with the same labelled generic representation

fn sculpted_convert_from<A, Indices>(a: A) -> Self

where A: LabelledGeneric, Self: Sized, <A as LabelledGeneric>::Repr: Sculptor<<Self as LabelledGeneric>::Repr, Indices>,

👎Deprecated: obsolete, transform_from instead

Converts from another type A into Self assuming that A and Self have labelled generic representations that can be sculpted into each other.

Note that this method tosses away the “remainder” of the sculpted representation. In other words, anything that is not needed from A gets tossed out.

fn transform_from<Src, Indices>(src: Src) -> Self

where Src: LabelledGeneric, Self: Sized, <Src as LabelledGeneric>::Repr: Sculptor<<Self as LabelledGeneric>::Repr, Indices>,

Converts from another type Src into Self assuming that Src and Self have labelled generic representations that can be sculpted into each other.

Note that this method tosses away the “remainder” of the sculpted representation. In other words, anything that is not needed from Src gets tossed out.

Object Safety

This trait is not object safe.

Implementors