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authorDave Gauer <dave@ratfactor.com>2021-05-13 19:48:10 -0400
committerDave Gauer <dave@ratfactor.com>2021-05-13 19:48:10 -0400
commit00f525c80f8a7785852092af246b28fe8fac1893 (patch)
tree9b9607e3cf7607aaa1ee8f0ab5a7364199c93492
parent469d4dfbf40dd5512f53ce1cb022e1aa4639443b (diff)
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add ex088 async 5 await
-rw-r--r--build.zig4
-rw-r--r--exercises/088_async5.zig47
-rw-r--r--patches/patches/088_async5.patch4
3 files changed, 55 insertions, 0 deletions
diff --git a/build.zig b/build.zig
index d8c4676..043bb2c 100644
--- a/build.zig
+++ b/build.zig
@@ -430,6 +430,10 @@ const exercises = [_]Exercise{
.main_file = "087_async4.zig",
.output = "1 2 3 4 5",
},
+ .{
+ .main_file = "088_async5.zig",
+ .output = "Example Title.",
+ },
};
/// Check the zig version to make sure it can compile the examples properly.
diff --git a/exercises/088_async5.zig b/exercises/088_async5.zig
new file mode 100644
index 0000000..523fa73
--- /dev/null
+++ b/exercises/088_async5.zig
@@ -0,0 +1,47 @@
+//
+// Sure, we can solve our async value problem with a global
+// variable. But this hardly seems like an ideal solution.
+//
+// So how do we REALLY get return values from async functions?
+//
+// The 'await' keyword waits for an async function to complete
+// and then captures its return value.
+//
+// fn foo() u32 {
+// return 5;
+// }
+//
+// var foo_frame = async foo(); // invoke and get frame
+// var value = await foo_frame; // await result using frame
+//
+// The above example is just a silly way to call foo() and get 5
+// back. But if foo() did something more interesting such as wait
+// for a network response to get that 5, our code would pause
+// until the value was ready.
+//
+// As you can see, async/await basically splits a function call
+// into two parts:
+//
+// 1. Invoke the function ('async')
+// 2. Getting the return value ('await')
+//
+// Also notice that a 'suspend' keyword does NOT need to exist in
+// a function to be called in an async context.
+//
+// Please use 'await' to get the string returned by
+// getPageTitle().
+//
+const print = @import("std").debug.print;
+
+pub fn main() void {
+ var myframe = async getPageTitle("http://example.com");
+
+ var value = ???
+
+ print("{s}\n", .{value});
+}
+
+fn getPageTitle(url: []const u8) []const u8 {
+ // Please PRETEND this is actually making a network request.
+ return "Example Title.";
+}
diff --git a/patches/patches/088_async5.patch b/patches/patches/088_async5.patch
new file mode 100644
index 0000000..7ce4fc6
--- /dev/null
+++ b/patches/patches/088_async5.patch
@@ -0,0 +1,4 @@
+39c39
+< var value = ???
+---
+> var value = await myframe;