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Diffstat (limited to 'exercises/048_methods2.zig')
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1 files changed, 71 insertions, 0 deletions
diff --git a/exercises/048_methods2.zig b/exercises/048_methods2.zig new file mode 100644 index 0000000..f97710d --- /dev/null +++ b/exercises/048_methods2.zig @@ -0,0 +1,71 @@ +// +// 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 |