## `Intl.DurationFormat` ⏲
## Stage 3 Update
#### Ujjwal Sharma (@ryzokuken) from Igalia
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## Act I: The bug 🐛
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```
1.4.3 Intl.DurationFormat.prototype.format ( duration )
...
3. Let record be ? ToPartialDuration(duration).
4. Let formatted be ? PartitionDurationFormatPattern(df, record).
```
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### `ToPartialDuration`
* Accepts: A "duration-like" (options bag, but could also be a `Duration` instance).
* Returns: A Partial Duration Record (Duration Record but with undefined).
* The rest of the code assumed no undefined fields, so we clearly needed a Duration Record instead. This was a bug.
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## Act II: The bugfix 🛠
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```diff
diff --git a/spec.emu b/spec.emu
index 40ccd8f..63b1749 100644
--- a/spec.emu
+++ b/spec.emu
@@ -323,7 +323,7 @@ contributors: Ujjwal Sharma, Younies Mahmoud
<emu-alg>
1. Let _df_ be *this* value.
1. Perform ? RequireInternalSlot(_df_, [[InitializedDurationFormat]]).
- 1. Let _record_ be ? ToPartialDuration(_duration_).
+ 1. Let _record_ be ? ToTemporalDurationRecord(_duration_).
1. Let _formatted_ be ? PartitionDurationFormatPattern(_df_, _record_).
1. Let _result_ be a new empty String.
1. For each element _part_ in _formatted_, in List order, do
@@ -341,7 +341,7 @@ contributors: Ujjwal Sharma, Younies Mahmoud
<emu-alg>
1. Let _df_ be *this* value.
1. Perform ? RequireInternalSlot(_df_, [[InitializedDurationFormat]]).
- 1. Let _record_ be ? ToPartialDuration(_duration_).
+ 1. Let _record_ be ? ToTemporalDurationRecord(_duration_).
1. Let _formatted_ be ? PartitionDurationFormatPattern(_df_, _record_).
1. Let _result_ be ArrayCreate(0).
1. Let _n_ be `0`.
```
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### `ToPartialDuration` -> `ToTemporalDurationRecord`
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### `ToTemporalDurationRecord`
* Accepts: A "duration-like" (options bag, but could also be a `Duration` instance as well as valid duration strings).
* Returns: A Duration Record (exactly what we needed).
* Since it was assumed to be a bug in the original spec text, I was keen to fix this ASAP to unblock implementations.
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### `ToTemporalDurationRecord` accepts strings ❗
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## Act III: The concern 🤔
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> I think it’s a big issue to assume that one stage 3 proposal will land before another - this one seems likely far simpler and faster than Temporal solely due to its size.
> If this proposal must wait for Temporal, that’s something plenary needs consensus on.
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## Two Problems
1. Proposal depends on Temporal.
2. There's a bug! String parsing shouldn't be allowed (especially without Temporal).
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## Act IV: The reconciliation 👀
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### Question: Does `DurationFormat` makes sense irrespective of Temporal?
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### Answer: Yes
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## Solution
* `DurationFormmat` will explicitly avoid depending on Temporal.
* This means only accepting options bags (and `Duration` objects by co-incidence).
* A follow-up should later add support for strings (and `Duration`s if needed), blocked on Temporal.
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## Question
How should we do this?
1. Merge the follow-on part into Temporal.
2. Split into two distinct Stage 3 proposals.
3. Move the follow-up part into a fresh proposal.
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# Thanks 🙏