Enhancing docs for selector and channel, from feedback and careful testing #1137
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Groxx
changed the title
…sting uber-go#1131 was merged with some mostly-minor feedback to tackle, and this almost completes it. I have not yet run integration tests against signal channel behavior when closed, and I'm not yet entirely happy with the docs around signal channels in general, but I think this is a net improvement worth merging.
yux0
approved these changes
Oct 5, 2021
Groxx
commented
Oct 5, 2021
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| Receive(ctx Context, valuePtr interface{}) (more bool) | ||
| Receive(ctx Context, valuePtr interface{}) (ok bool) |
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more consistent ok/more use across the board to match the go language reference's variable names.
Groxx
commented
Oct 5, 2021
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| // case i, more := <- chA: | ||
| // if more { | ||
| // counter += i | ||
| // } | ||
| // case i, more := <- chB: | ||
| // if more { | ||
| // counter += i | ||
| // } | ||
| // case x := <- chA: | ||
| // counter += i | ||
| // case y := <- chB: | ||
| // counter += i |
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decided the ok/more/subtle difference in behavior wasn't worth addressing, as it made the code less normal and more complex.
for chans that are never closed and only contain the right values (no Receive errors), which is often the case in real code, both before and after behave identically.
Groxx
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Oct 5, 2021
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| // select { | ||
| // case v, more := <- aChannel: ok = true | ||
| // default: ok = false | ||
| // case received, ok := <- aChannel: | ||
| // if ok { | ||
| // *valuePtr = received | ||
| // } | ||
| // more = ok | ||
| // default: | ||
| // // no value was read | ||
| // ok = false | ||
| // // but the read would have blocked, so the channel is not closed | ||
| // more = true | ||
| // } | ||
| // | ||
| // But if your output values are zero values, this is equivalent to a simpler form: | ||
| // select { | ||
| // case value, ok := <- aChannel: | ||
| // more = ok | ||
| // default: | ||
| // // no value was read | ||
| // ok = false | ||
| // // but the read would have blocked, so the channel is not closed | ||
| // more = true | ||
| // } |
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This took a bit of time to nail down precisely :| it's a bit odd (I don't believe I've ever seen this kind of select statement in normal go code), but may be useful in some cases.
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#1131 was merged with some mostly-minor feedback to tackle, and this almost completes it.
I have not yet run integration tests against signal channel behavior when closed, and I'm
not yet entirely happy with the docs around signal channels in general, but I think this
is a net improvement worth merging.