Trait TupleLenEqTo 

pub trait TupleLenEqTo<T: TupleLike>: TupleLike { }

A Marker trait to indicate that two tuple types have the same number of elements.

FIXME: Once the generic_const_exprs feature and the associated_const_equality feature are stabilized, this trait is no longer needed. Instead, we can write:

use tuplez::TupleLike;

fn use_tuple<T, U>(t: T, u: U)
where
    T: TupleLike,
    U: TupleLike<LEN = { T::LEN }>,
{
    // ...
}

Example

Use with tuple_t! macro to constrain the number of elements of the tuple.

use tuplez::{tuple, tuple_t, TupleLenEqTo, TupleLike};

fn only_accept_5_elements<T>(_: T)
where
    T: TupleLenEqTo<tuple_t!((); 5)>
{
}

let tup4 = tuple!(1, 2.0, "3", 4);
// only_accept_5_elements(tup4);    // Error: the trait bound is not satisfied
let tup5 = tup4.push_back('5');
only_accept_5_elements(tup5);       // Ok
let tup6 = tup5.push_back(6.0);
// only_accept_5_elements(tup6);    // Error: the trait bound is not satisfied

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl TupleLenEqTo<Unit> for Unit

impl<First1, Other1, First2, Other2> TupleLenEqTo<Tuple<First2, Other2>> for Tuple<First1, Other1>

where Other1: TupleLenEqTo<Other2>, Other2: TupleLike,