# Description
This changes the behavior of `tee` to be more transparent when given a
value that isn't a list or range. Previously, anything that wasn't a
byte stream would converted to a list stream using the iterator
implementation, which led to some surprising results. Instead, now, if
the value is a string or binary, it will be treated the same way a byte
stream is, and the output of `tee` is a byte stream instead of the
original value. This is done so that we can synchronize with the other
thread on collect, and potentially capture any error produced by the
closure.
For values that can't be converted to streams, the closure is just run
with a clone of the value instead on another thread. Because we can't
wait for the other thread, there is no way to send an error back to the
original thread, so instead it's just written to stderr using
`report_error_new()`.
There are a couple of follow up edge cases I see where byte streams
aren't necessarily treated exactly the same way strings are, but this
should mostly be a good experience.
Fixes#13489.
# User-Facing Changes
Breaking change.
- `tee` now outputs and sends string/binary stream for string/binary
input.
- `tee` now outputs and sends the original value for any other input
other than lists/ranges.
# Tests + Formatting
Added for new behavior.
# After Submitting
- [ ] release notes: breaking change, command change
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# Description
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This is inspired by the Unix tee command, but significantly more
powerful. Rather than just writing to a file, you can do any kind of
stream operation that Nushell supports within the closure.
The equivalent of Unix `tee -a file.txt` would be, for example, `command
| tee { save -a file.txt }` - but of course this is Nushell, and you can
do the same with structured data to JSON objects, or even just run any
other command on the system with it.
A `--stderr` flag is provided for operating on the stderr stream from
external programs. This may produce unexpected results if the stderr
stream is not then also printed by something else - nushell currently
doesn't. See #11929 for the fix for that.
# User-Facing Changes
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helps us keep track of breaking changes. -->
If someone was using the system `tee` command, they might be surprised
to find that it's different.
# Tests + Formatting
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- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`
# After Submitting
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