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//
// Now that we've seen how methods work, let's see if we can help
// our elephants out a bit more with some Elephant methods.
//
const std = @import("std");
const Elephant = struct {
letter: u8,
tail: ?*Elephant = null,
visited: bool = false,
// New Elephant methods!
pub fn getTail(self: *Elephant) *Elephant {
return self.tail.?; // Remember, this is means "orelse unreachable"
}
pub fn hasTail(self: *Elephant) bool {
return (self.tail != null);
}
pub fn visit(self: *Elephant) void {
self.visited = true;
}
pub fn print(self: *Elephant) void {
// Prints elephant letter and [v]isited
var v: u8 = if (self.visited) 'v' else ' ';
std.debug.print("{u}{u} ", .{ self.letter, v });
}
};
pub fn main() void {
var elephantA = Elephant{ .letter = 'A' };
var elephantB = Elephant{ .letter = 'B' };
var elephantC = Elephant{ .letter = 'C' };
// Link the elephants so that each tail "points" to the next.
elephantA.tail = &elephantB;
elephantB.tail = &elephantC;
visitElephants(&elephantA);
std.debug.print("\n", .{});
}
// This function visits all elephants once, starting with the
// first elephant and following the tails to the next elephant.
fn visitElephants(first_elephant: *Elephant) void {
var e = first_elephant;
while (true) {
e.print();
e.visit();
// Get the next elephant or stop.
if (e.hasTail()) {
e = e.???; // Which method do we want here?
} else {
break;
}
}
}
// Bonus: Zig's enums can also have methods! Can you find
// one in the wild? If you can, mention it along with your
// name or alias in a comment below this one and make a
// pull request on GitHub for a piece of eternal Ziglings
// glory. The first five (5) PRs will be accepted!
//
// 1) drforester - I found one in the Zig source:
// https://github.com/ziglang/zig/blob/041212a41cfaf029dc3eb9740467b721c76f406c/src/Compilation.zig#L2495
//
// 2) bbuccianti - I found one!
// https://github.com/ziglang/zig/blob/master/lib/std/debug.zig#L477
//
// 3) GoldsteinE - Found many, here's one
// https://github.com/ziglang/zig/blob/ce14bc7176f9e441064ffdde2d85e35fd78977f2/lib/std/target.zig#L65
//
// 4) SpencerCDixon - Love this language so far :-)
// https://github.com/ziglang/zig/blob/a502c160cd51ce3de80b3be945245b7a91967a85/src/zir.zig#L530
//
// 5) tomkun - here's another enum method
// https://github.com/ziglang/zig/blob/4ca1f4ec2e3ae1a08295bc6ed03c235cb7700ab9/src/codegen/aarch64.zig#L24
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