proposal: bytes, strings: `TrimStart` and `TrimEnd` replacing `TrimLeft` and `TrimRight`

[hajimehoshi]

TrimLeft and TrimRight implicitly assumes a left-to-right writing system, but this is odd. Actually a string literal can include right-to-left languages and how to show them depends on editors. We don't have to (or cannot) determine visible directions of texts.

So, what about adding new functions TrimStart and TrimEnd as aliases to TrimLeft and TrimRight, and deprecating TrimLeft and TrimRight? This naming is the same way as CSS (e.g. padding-inline-start for padding-left)

The replacing targets are:

• bytes.TrimLeft
• bytes.TrimLeftFunc
• bytes.TrimRight
• bytes.TrimRightFunc
• strings.TrimLeft
• strings.TrimLeftFunc
• strings.TrimRight
• strings.TrimRightFunc

[shmsr]

Yes, I agree. It'd be similar to Rust, i.e., trim_left has been deprecated since 1.33.0, and it is recommended to use trim_start instead.

https://doc.rust-lang.org/std/string/struct.String.html#method.trim_left

[rsc]

This seems like a lot of churn for not too much benefit.
Deprecating old names creates IDE prompts and takes up developer time.
The bigger problem with these functions is that people think TrimLeft is TrimPrefix, and calling it TrimStart will not make that problem go away. It might make the problem worse.

[rsc]

This proposal has been added to the active column of the proposals project
and will now be reviewed at the weekly proposal review meetings.
— rsc for the proposal review group

[rsc]

Based on the discussion above, this proposal seems like a likely decline.
— rsc for the proposal review group

[itchyny]

The bigger problem with these functions is that people think TrimLeft is TrimPrefix, and calling it TrimStart will not make that problem go away. It might make the problem worse.

I agree that it still causes confusion between Prefix and Start. But how about adding Any suffix to the functions with cutset argument?

substr	cutset	func
Contains	ContainsAny	#54386
Index	IndexAny	IndexFunc
LastIndex	LastIndexAny	LastIndexFunc
TrimPrefix	TrimLeft → TrimPrefixAny	TrimLeftFunc → TrimPrefixFunc
TrimSuffix	TrimRight → TrimSuffixAny	TrimRightFunc → TrimSuffixFunc

[rsc]

No change in consensus, so declined.
— rsc for the proposal review group