add ex090 async 7

This commit is contained in:
Dave Gauer 2021-06-14 15:39:49 -04:00
parent 37ca10ab36
commit 34af14ca7b
3 changed files with 51 additions and 0 deletions

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@ -438,6 +438,10 @@ const exercises = [_]Exercise{
.main_file = "089_async6.zig",
.output = ".com: Example Title, .org: Example Title.",
},
.{
.main_file = "090_async7.zig",
.output = "beef? BEEF!",
},
};
/// Check the zig version to make sure it can compile the examples properly.

43
exercises/090_async7.zig Normal file
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@ -0,0 +1,43 @@
//
// Remember how a function with 'suspend' is async and calling an
// async function without the 'async' keyword makes the CALLING
// function async?
//
// fn fooThatMightSuspend(maybe: bool) void {
// if (maybe) suspend {}
// }
//
// fn bar() void {
// fooThatMightSuspend(true); // Now bar() is async!
// }
//
// But if you KNOW the function won't suspend, you can make a
// promise to the compiler with the 'nosuspend' keyword:
//
// fn bar() void {
// nosuspend fooThatMightSuspend(false);
// }
//
// If the function does suspend and YOUR PROMISE TO THE COMPILER
// IS BROKEN, the program will panic at runtime, which is
// probably better than you deserve, you oathbreaker! >:-(
//
const print = @import("std").debug.print;
pub fn main() void {
// The main() function can not be async. But we know
// getBeef() will not suspend with this particular
// invocation. Please make this okay:
var my_beef = getBeef(0);
print("beef? {X}!\n", .{my_beef});
}
fn getBeef(input: u32) u32 {
if (input > 0xDEAD) {
suspend {}
}
return 0xBEEF;
}

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@ -0,0 +1,4 @@
32c32
< var my_beef = getBeef(0);
---
> var my_beef = nosuspend getBeef(0);