rust-ape-example/src/bin/generics_gen_fn.rs

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// ./src/generics/gen_fn.md
struct A; // Concrete type `A`.
struct S(A); // Concrete type `S`.
struct SGen<T>(T); // Generic type `SGen`.
// The following functions all take ownership of the variable passed into
// them and immediately go out of scope, freeing the variable.
// Define a function `reg_fn` that takes an argument `_s` of type `S`.
// This has no `<T>` so this is not a generic function.
fn reg_fn(_s: S) {}
// Define a function `gen_spec_t` that takes an argument `_s` of type `SGen<T>`.
// It has been explicitly given the type parameter `A`, but because `A` has not
// been specified as a generic type parameter for `gen_spec_t`, it is not generic.
fn gen_spec_t(_s: SGen<A>) {}
// Define a function `gen_spec_i32` that takes an argument `_s` of type `SGen<i32>`.
// It has been explicitly given the type parameter `i32`, which is a specific type.
// Because `i32` is not a generic type, this function is also not generic.
fn gen_spec_i32(_s: SGen<i32>) {}
// Define a function `generic` that takes an argument `_s` of type `SGen<T>`.
// Because `SGen<T>` is preceded by `<T>`, this function is generic over `T`.
fn generic<T>(_s: SGen<T>) {}
fn part0() {
// Using the non-generic functions
reg_fn(S(A)); // Concrete type.
gen_spec_t(SGen(A)); // Implicitly specified type parameter `A`.
gen_spec_i32(SGen(6)); // Implicitly specified type parameter `i32`.
// Explicitly specified type parameter `char` to `generic()`.
generic::<char>(SGen('a'));
// Implicitly specified type parameter `char` to `generic()`.
generic(SGen('c'));
}
pub fn main() {
part0();
}