feat: add readonly flag
#92
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| /** | ||
| * Whether the attribute is read-only. | ||
| */ | ||
| readonly?: boolean; |
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What does it mean for an attribute to be read-only? afaiu, there really shouldn't be such a thing.
If there's a use for this, say to cover for the lack of CSS custom state, should we highlight that in the description?
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an element might observe changes in that attribute and reject values it finds icky, resetting to the previous known-good value, or removing the attribute.
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@justinfagnani Would this PR be clear to merge if it was only adding this to properties? I can create a new PR if necessary, but it would be nice to get this added for properties to unblock the CEM analyzer support. If @bennypowers or others feel strongly about usage with attributes, perhaps we can create a new issue for that discussion?
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If youre using @custom-elements-manifest/analyzer, you can already support this via a plugin
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I would go with this if it were for properties only to avoid semantics questions about "readonly" attributes.
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@thepassle one tool emitting this property doesn't mean that other tools know to read it.
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True, but they mentioned cem analyzer being blocked, which it isnt
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Thanks to both of you for the responses. I am using that analyzer, and was able to find the plugin, so that does unblock me personally. My use case for this particular feature is Angular Framework integration, and I need to ensure that readonly properties can't be bound as an @Input().
I do still think it would be a good addition to the spec, so I'll try to get a PR up soon. Enough people have asked and it encodes a real semantic of the language. If it were added here, support could be added to the analyzer without a plugin, and other tools as well.
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Id be okay with adding readonly for fields, im also unsure about attributes. Perhaps we can indeed address that in a separate discussion.
@MikeMatusz If and when that change has landed in the schema, would you be willing to contribute your plugin logic to cem/a?
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It's not actually my logic, the original author of this PR appears to have written the plugin I found (https://github.com/bennypowers/cem-plugins/tree/main/plugins/cem-plugin-readonly), but I'd be more than willing to help contribute it to cem/a unless @bennypowers would prefer to do it himself. This spec and that analyzer have proven extremely useful to me.
Closes #34