2023-03-01 20:46:05 +01:00
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---
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title: 'Request For Comments: Forward Slash as Separator'
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author: Natalie Weizenbaum
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tags: blog
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2023-03-03 16:39:31 +01:00
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date: 2019-05-06 16:15:00 -8
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2023-03-01 20:46:05 +01:00
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---
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Early on in Sass's history, the decision was made to use `/` as a division
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operator, since that was (and is) by far the most common representation across
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programming languages. The `/` character was used in very few plain CSS
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properties, and for those it was an optional shorthand. So Sass defined [a set
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of heuristics][] that defined when `/` would be rendered as a literal slash
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versus treated as an operator.
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[a set of heuristics]: /documentation/operators/numeric#slash-separated-values
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For a long time, these heuristics worked pretty well. In recent years, however,
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new additions to CSS such as [CSS Grid][] and [CSS Color Level 4][] have been
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using `/` as a separator increasingly often. Using the same character for both
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division and slash-separation is becoming more and more annoying to users, and
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will likely eventually become untenable.
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[CSS Grid]: https://developer.mozilla.org/en-US/docs/Web/CSS/grid-row
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[CSS Color Level 4]: https://drafts.csswg.org/css-color/#rgb-functions
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As such, we're planning to redefine `/` to be _only_ a separator. Rather than
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creating an unquoted string (as it currently does when at least one operand
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isn't a number), it will create a list with a new slash separator. For example,
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`1 / 2 / 3` will be a three-element slash-separated list. Division will instead
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be written as a function, `divide()` (or `math.div()` in [the new module
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system][]).
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[the new module system]: /blog/request-for-comments-module-system-proposal
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## Rollout
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This is a major breaking change to existing Sass semantics, so we'll roll it out
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in a three-stage process:
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1. The first stage won't introduce any breaking changes. It will:
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- Add a `divide()` function which will work exactly like the `/` operator
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does today, except that it will produce deprecation warnings for any
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non-number arguments.
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- Add slash-separated lists to Sass's object models, _without_ a literal
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syntax for creating them. That will come later, since it would otherwise be
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a breaking change.
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- Add a `slash-list()` function that will create slash-separated lists.
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- Produce deprecation warnings for all `/` operations that are interpreted as
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division.
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2. The second stage _will_ be a breaking change. It will:
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- Make `/` exclusively a list separator.
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- Make `divide()` throw errors for non-number arguments.
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- Deprecate the `slash-list()` function, since it will now be redundant.
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3. The third stage will just remove the `slash-list()` function. This is not a
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priority, and will be delayed until the next major version release.
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## Giving Feedback
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If you want more details on exactly how the proposed behavior will work, [head
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over to the Sass language repo and read the full
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proposal](https://github.com/sass/sass/blob/main/accepted/slash-separator.md).
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You can skip the Background and Summary sections, since they're included above.
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Be aware, though, that it's written to be a specification; it's a great for
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figuring out how exactly an edge case should work, but it's not as
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conversational as the sections quoted above.
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If you have any issues with the proposal as written, or if it doesn't cover a
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use-case that's important to you, [please bring that up in the Sass language
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issue
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tracker](https://github.com/sass/sass/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+label%3A%22proposal%3A+slash+separator%22).
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We'll be leaving it open for discussion for at least two weeks before we mark
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the proposal as "accepted" and move on to the implementation phase.
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Please be aware, though, that while we welcome community feedback, the design of
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Sass is ultimately in the hands of the language team. We'll absolutely consider
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the perspectives and use-cases of users who speak up, but it's also our job to
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consider all the users who are new to Sass or even to CSS and who don't yet know
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to read blogs or comment on issue trackers. Remember that our careful
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decision-making made Sass what it is today, and have patience with us if we
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don't make the decisions you would have!
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