Comment by tcfhgj
Comment by tcfhgj 18 hours ago
yes, you can:
runtime.block_on(async { })
Comment by tcfhgj 18 hours ago
yes, you can:
runtime.block_on(async { })
> In Zig, a function that does IO can be called the same way whether or not it performs async operations or not.
no, you can't, you need to pass a IO parameter
You will need to pass that for synchronous IO as well. All IO in the standard library is moving to the Io interface. Sync and async.
If I want to call a function that does asynchronous IO, I'll use:
foo(io, ...);
foo(io, ...);
io.async(foo, .{ io, ... });
try io.concurrent(foo, .{ io, ... });
Here's a problem with that:
Cannot start a runtime from within a runtime. This happens because a function (like `block_on`) attempted to block the current thread while the thread is being used to drive asynchronous tasks.
Fixed it for you
https://play.rust-lang.org/?version=stable&mode=debug&editio...
But that's the thing, idiomatic Rust sync code almost never passes around handles, even when they need to do I/O.
You might be different, and you might start doing that in your code, but almost none of either std or 3rd party libraries will cooperate with you.
The difference with Zig is not in its capabilities, but rather in how the ecosystem around its stdlib is built.
The equivalent in Rust would be if almost all I/O functions in std would be async; granted that would be far too expensive and disruptive given how async works.
> Because they don't use async inside.
But they use I/O inside, and we arrive at this issue:
I'm writing async, and I need to call std::fs::read. I can't, because it blocks the thread; I could use spawn_blocking but that defeats the purpose of async. So instead I have to go look for a similar function but of the other color, probably from tokio.
In Zig, if you're writing sync, you call the standard library function for reading files. If you're writing async, you call the same library function for reading files. Then, the creator of the `io` object decides whether the whole thing will be sync or async.
Let me rephrase, you can't call it like any other function.
In Zig, a function that does IO can be called the same way whether or not it performs async operations or not. And if those async operations don't need concurrency (which Zig expresses separately to asynchronicity), then they'll run equally well on a sync Io runtime.