nushell/crates/nu-protocol
Bob Hyman 570175f95d
Fix duration type to not report months or years (#9632)
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This PR should close #8036, #9028 (in the negative) and #9118.

Fix for #9118 is a bit pedantic.  As reported, the issue is:
```
> 2023-05-07T04:08:45+12:00 - 2019-05-10T09:59:12+12:00
3yr 12month 2day 18hr 9min 33sec
```
with this PR, you now get:
```
> 2023-05-07T04:08:45+12:00 - 2019-05-10T09:59:12+12:00
208wk 1day 18hr 9min 33sec
```
Which is strictly correct, but could still fairly be called "weird date
arithmetic".

# Description
* [x] Abide by constraint that Value::Duration remains a number of
nanoseconds with no additional fields.
* [x] `to_string()` only displays weeks .. nanoseconds. Duration doesn't
have base date to compute months or years from.
* [x] `duration | into record` likewise only has fields for weeks ..
nanoseconds.
* [x] `string | into duration` now accepts compound form of duration
to_string() (e.g '2day 3hr`, not just '2day')
* [x] `duration | into string` now works (and produces the same
representation as to_string(), which may be compound).

# User-Facing Changes
## duration -> string -> duration
Now you can "round trip" an arbitrary duration value: convert it to a
string that may include multiple time units (a "compound" value), then
convert that string back into a duration. This required changes to
`string | into duration` and the addition of `duration | into string'.
```
> 2day + 3hr
2day 3hr # the "to_string()" representation (in this case, a compound value)
> 2day + 3hr | into string
2day 3hr # string value
> 2day + 3hr | into string | into duration
2day 3hr # round-trip duration -> string -> duration
```
Note that `to nuon` and `from nuon` already round-tripped durations, but
use a different string representation.

## potentially breaking changes
* string rendering of a duration no longer has 'yr' or 'month' phrases.
* record from `duration | into record` no longer has 'year' or 'month'
fields.
The excess duration is all lumped into the `week` field, which is the
largest time unit you can
convert to without knowing the datetime from which the duration was
calculated.

Scripts that depended on month or year time units on output will need to
be changed.

### Examples
```
> 365day
52wk 1day
## Used to be: 
## 1yr

> 365day | into record
╭──────┬────╮
│ week │ 52 │
│ day  │ 1  │
│ sign │ +  │
╰──────┴────╯

## used to be:
##╭──────┬───╮
##│ year │ 1 │
##│ sign │ + │
##╰──────┴───╯

> (365day + 4wk + 5day + 6hr + 7min + 8sec + 9ms + 10us + 11ns)
56wk 6day 6hr 7min 8sec 9ms 10µs 11ns
## used to be:
## 1yr 1month 3day 6hr 7min 8sec 9ms 10µs 11ns
## which looks reasonable, but was actually only correct in 75% of the years and 25% of the months in the last 4 years.

> (365day + 4wk + 5day + 6hr + 7min + 8sec + 9ms + 10us + 11ns) | into record
╭─────────────┬────╮
│ week        │ 56 │
│ day         │ 6  │
│ hour        │ 6  │
│ minute      │ 7  │
│ second      │ 8  │
│ millisecond │ 9  │
│ microsecond │ 10 │
│ nanosecond  │ 11 │
│ sign        │ +  │
╰─────────────┴────╯
```
Strictly speaking, these changes could break an existing user script.
Losing years and months as time units is arguably a regression in
behavior.

Also, the corrected duration calculation could break an existing script
that was calibrated using the old algorithm.

# Tests + Formatting
```
> toolkit check pr
```
- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

# After Submitting
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---------

Co-authored-by: Bob Hyman <bobhy@localhost.localdomain>
2023-08-08 06:24:09 -05:00
..
src Fix duration type to not report months or years (#9632) 2023-08-08 06:24:09 -05:00
tests Fix duration type to not report months or years (#9632) 2023-08-08 06:24:09 -05:00
Cargo.toml Fix duration type to not report months or years (#9632) 2023-08-08 06:24:09 -05:00
LICENSE Fix rest of license year ranges (#8727) 2023-04-04 09:03:29 +12:00
README.md Add nu-protocol 2021-09-02 13:29:43 +12:00

nu-protocol

The nu-protocol crate holds the definitions of structs/traits that are used throughout Nushell. This gives us one way to expose them to many other crates, as well as make these definitions available to each other, without causing mutually recursive dependencies.