Define reserved identifiers #1038

eemeli · 2025-02-21T09:25:18Z

Fixes #1033 with the text proposed there by @macchiati. The changes to the making-messages-invalid line proposed in #1025 are left out.

macchiati

I don't think this completely solves problem, but this is big step in the right direction.

aphillips · 2025-02-21T15:36:31Z

spec/intro.md

+> [!NOTE]
+> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,
+> _options_ to _default functions_, _attributes_, and _markup_.


This is a normative change, since it removes a normative SHOULD (albeit to function authors and which cannot be tested). Why not keep the normative level intact? We can do a wording change, if desired.

I'm not sure about "markup", since we don't define markup.

We could make it a bit tighter:

Suggested change

> [!NOTE]

> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,

> _options_ to _default functions_, _attributes_, and _markup_.

> [!NOTE]

> Use a namespace for all _identifiers_ defined by an implementation

> or in the _names_ of custom _functions_, _attributes_, or _markup_ defined by users.

The fuzziness of 'implementation' and 'user' gets in the way here. I read 'custom' as 'not defined by this spec. I read 'users' as 'users of an implementation', including that implementation's custom functions, etc.

Given that the SHOULD is effectively untestable, I don't think changing it to "strongly advised" is that significant a change.

I'd be fine with leaving un-namespaced markup as explicitly not reserved.

I'd be fine with leaving un-namespaced markup as explicitly not reserved.

I disagree: we currently don't define any standard markup, but we could in the future (same with attributes). So the same principles for functions and attributes apply.

macchiati · 2025-02-21T15:58:11Z

spec/intro.md

-_function_ _identifiers_ and _function_ _option_ _identifiers_
-which satisfy either of the following two requirements:
+**_<dfn>Reserved identifiers</dfn>_** are those that satisfy at least one of the following conditions:
+
 - Includes no _namespace_,
  and has a _name_ consisting of characters in the ranges a-z, A-Z, and 0-9,
  and the characters U+002E FULL STOP `.`, U+002D HYPHEN-MINUS `-`, and U+005F LOW LINE `_`.
 - Uses a _namespace_ consisting of a single character in the ranges a-z and A-Z.



Text flows much better if we add another definition:

Suggested change

**_<dfn>Custom identifiers</dfn>_** are all those identifiers that are not _reserved identifiers_:

This stuff seems to belong better in syntax.md than in the body of the stability policy. We have a whole section about names and identifiers there and that's where most readers would expect to find definitions like these. Then the stability policy can focus on it's job of forbidding/permitting certain things found in the specification

I agree with Addison. Defining reserved identifier here makes sense, but going beyond that would be a bit much.

I agree, in the sense that "Includes no namespace,
and has a name consisting of characters in the ranges a-z, A-Z, and 0-9,
and the characters U+002E FULL STOP ., U+002D HYPHEN-MINUS -, and U+005F LOW LINE _." should never have been just in the body; it should have had a syntax definition.

That is, I think we need to define the 'reserved identifiers' and the 'custom identifiers', and ideally they would be in the abnf and not here.

The message.abnf only includes rules that are required for the definition of the message rule. We already have some ABNF rules sprinkled elsewhere in the spec:

currency_code

number-literal

digit-size-option

integer

u-locale-option

ok, makes sense.

macchiati · 2025-02-21T15:59:02Z

spec/intro.md

 - Includes no _namespace_,
  and has a _name_ consisting of characters in the ranges a-z, A-Z, and 0-9,
  and the characters U+002E FULL STOP `.`, U+002D HYPHEN-MINUS `-`, and U+005F LOW LINE `_`.
 - Uses a _namespace_ consisting of a single character in the ranges a-z and A-Z.

-All other _identifiers_ in these categories are reserved for the use of implementations or users.
+Updates to this specification will only reserve, define, or require _reserved identifiers_.
+All _identifiers_ other than _reserved identifiers_ are available for the use of implementations or users.


Suggested change

All _identifiers_ other than _reserved identifiers_ are available for the use of implementations or users.

All _custom identifiers_ are available for the use of implementations or users.

macchiati · 2025-02-21T16:00:50Z

spec/intro.md

-> SHOULD use a _namespace_ as part of their _identifiers_
-> to help avoid collisions with other implementations.
+> [!NOTE]
+> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,


Suggested change

> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,

> Implementers and users are strongly advised to only use _custom identifiers_ in custom _functions_,

This changes the meaning. There are two things going on here:

Non-default functions should use a namespace. <- this is not normative but is good advice

They can omit the namespace by choosing names that include non-reserved identifier characters too, so separately:

Non-default functions should use custom identifiers

We also have to be careful to say that we mean for the function name.

{$foo :custom:function option=|option has a 'reserved' identifier which we want to encourage|}

macchiati · 2025-02-21T16:09:51Z

spec/intro.md

+> [!NOTE]
+> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,
+> _options_ to _default functions_, _attributes_, and _markup_.


The fuzziness of 'implementation' and 'user' gets in the way here. I read 'custom' as 'not defined by this spec. I read 'users' as 'users of an implementation', including that implementation's custom functions, etc.

macchiati · 2025-02-21T18:54:11Z

spec/intro.md

-_function_ _identifiers_ and _function_ _option_ _identifiers_
-which satisfy either of the following two requirements:
+**_<dfn>Reserved identifiers</dfn>_** are those that satisfy at least one of the following conditions:
+
 - Includes no _namespace_,
  and has a _name_ consisting of characters in the ranges a-z, A-Z, and 0-9,
  and the characters U+002E FULL STOP `.`, U+002D HYPHEN-MINUS `-`, and U+005F LOW LINE `_`.
 - Uses a _namespace_ consisting of a single character in the ranges a-z and A-Z.



ok, makes sense.

macchiati · 2025-02-21T19:20:33Z

spec/intro.md

+> [!NOTE]
+> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,
+> _options_ to _default functions_, _attributes_, and _markup_.


I'd be fine with leaving un-namespaced markup as explicitly not reserved.

I disagree: we currently don't define any standard markup, but we could in the future (same with attributes). So the same principles for functions and attributes apply.

aphillips · 2025-02-21T20:20:17Z

Closing this in favor of #1040

Define reserved identifiers

11574f8

eemeli requested review from aphillips and macchiati February 21, 2025 09:25

macchiati approved these changes Feb 21, 2025

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aphillips added blocker Blocks the release normative Issue affects normative text in the specification specification Issue affects the specification LDML47 LDML 47 Release (Stable) labels Feb 21, 2025

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Define reserved identifiers #1038

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aphillips commented Feb 21, 2025



	_<dfn>Custom identifiers</dfn>_ are all those identifiers that are not _reserved identifiers_:

	All _identifiers_ other than _reserved identifiers_ are available for the use of implementations or users.
	All _custom identifiers_ are available for the use of implementations or users.

	> Implementers and users are strongly advised to namespace all _identifiers_ used in custom _functions_,
	> Implementers and users are strongly advised to only use _custom identifiers_ in custom _functions_,

Define reserved identifiers #1038

Define reserved identifiers #1038

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eemeli commented Feb 21, 2025

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aphillips commented Feb 21, 2025