59 lines
1.7 KiB
Zig
59 lines
1.7 KiB
Zig
//
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// Six Facts:
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//
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// 1. The memory space allocated to your program for the
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// invocation of a function and all of its data is called a
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// "stack frame".
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//
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// 2. The 'return' keyword "pops" the current function
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// invocation's frame off of the stack (it is no longer needed)
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// and returns control to the place where the function was
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// called.
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//
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// fn foo() void {
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// return; // Pop the frame and return control
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// }
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//
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// 3. Like 'return', the 'suspend' keyword returns control to the
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// place where the function was called BUT the function
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// invocation's frame remains so that it can regain control again
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// at a later time. Functions which do this are "async"
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// functions.
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//
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// fn fooThatSuspends() void {
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// suspend {} // return control, but leave the frame alone
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// }
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//
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// 4. To call any function in async context and get a reference
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// to its frame for later use, use the 'async' keyword:
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//
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// var foo_frame = async fooThatSuspends();
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//
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// 5. If you call an async function without the 'async' keyword,
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// the function FROM WHICH you called the async function itself
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// becomes async! In this example, the bar() function is now
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// async because it calls fooThatSuspends(), which is async.
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//
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// fn bar() void {
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// fooThatSuspends();
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// }
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//
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// 6. The main() function cannot be async!
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//
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// Given facts 3 and 4, how do we fix this program (broken by facts
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// 5 and 6)?
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//
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const print = @import("std").debug.print;
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pub fn main() void {
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// Additional Hint: you can assign things to '_' when you
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// don't intend to do anything with them.
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_ = async foo();
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}
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fn foo() void {
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print("foo() A\n", .{});
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suspend {}
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print("foo() B\n", .{});
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}
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