Non-throwing channel::read and channel::write

[anarthal]

Would it be possible to have functions that don't throw, but return an error code, on cancellation?

[klemens-morgenstern]

There are a few solutions

1. overload that's non-throwing
2. make interrupt return a default constructed value if it's trivial
3. make all of async system::result aware.

[anarthal]

2. sounds bad. 1. and 3. sound better. 3. is the one that sounds best.

[klemens-morgenstern]

What's bad about (2) ? The value gets ignored anyhow, so a channel<int> could just return 0.

[klemens-morgenstern]

interrupt_await could do (2) when used with select. Value gets ignored. If of course can't do that with regular read/write.

(1) would not work for non-default ctor-able T, so I think I should

add (2) for interrupt await & (3) for channel's only. I don't think stuff like promise<result<void, std::exception_ptr>> is necessary for now, but might be interesting.

[anarthal]

2. seems to not cover default-constructible types, either, unless I'm missing something.

I'd go for promise<result<T>> read(std::nothrow) or similar.

[klemens-morgenstern]

Is this really a general issue or rather one concerning using channels in a select statement?

[anarthal]

In my case it was just with channels + select. I don't know enough about the library to say if this could happen under more situations.