Revert typed SvelteComponent, add SvelteComponentTyped instead #5738
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`const a: typeof SvelteComponent = ASubclassOfSvelteComponent` throws errors, which means existing usages are broken. To prevent this, the changes to a typed `SvelteComponent` are reverted. Instead a new `SvelteComponentTyped` class is added, which should be used for typing instead.
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I don't quite understand why there's a |
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Maybe add a code comment that they're separated because of microsoft/TypeScript#41770 and a TODO to combine the components in Svelte 4.0.0? |
Good point, I added some docs.
Honestly I'm not sure if this is even a bug, it might also be as designed. I want to wait on a response from the TS team before adding a comment like this. |
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Thanks for adding the comments. Makes sense not to call it a bug for now. The issue might still be useful for reference even if designed that way, but there's enough comments that I think it's fine without too. Would adding a TODO to combine the classes in 4.0 make sense? I was under the impression that a new Typed class was created to maintain backwards compatibility, but it's not what we would do if starting from scratch. |
Yes it's for backwards compatibility and ease of use - if it's not a TS error but "works as designed", people would have to write |
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This looks good to me. Thanks for hopping on it so quickly Should we add something in The only other question I had is whether |
I was thinking about that, too. I first want to see if things turn out well now before making this more public.
My thoughts as well 😄 I chose it because it matches the postfix-style of |
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TS team confirmed that this works as designed, so we need to make with this change. |
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| @@ -11,7 +11,7 @@ It's the last "What's new in Svelte" of the year and there's lots to celebrate! | |||
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| 1. `$$props`, `$$restProps`, and `$$slots` are all now supported in custom web components (**3.29.5**, [Example](https://svelte.dev/repl/ad8e6f39cd20403dacd1be84d71e498d?version=3.29.5)) and `slot` components now support spread props: `<slot {...foo} />` (**3.30.0**) | |||
| 2. A new `hasContext` lifecycle function makes it easy to check whether a `key` has been set in the context of a parent component (**3.30.0** & **3.30.1**, [Docs](https://svelte.dev/docs#hasContext)) | |||
| 3. `SvelteComponent` is now typed which makes it easier to add typed classes that extend base Svelte Components. Component library and framework authors rejoice! An example: `export class YourComponent extends SvelteComponent<{aProp: boolean}, {click: MouseEvent}, {default: {aSlot: string}}> {}` (**3.30.0**, [RFC](https://github.com/sveltejs/rfcs/pull/37)) | |||
| 3. There is now a new `SvelteComponentTyped` class which makes it easier to add strongly typed components that extend base Svelte components. Component library and framework authors rejoice! An example: `export class YourComponent extends SvelteComponentTyped<{aProp: boolean}, {click: MouseEvent}, {default: {aSlot: string}}> {}` (**3.30.0**, [RFC](https://github.com/sveltejs/rfcs/pull/37)) | |||
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Was this broken to begin with? Otherwise this is a breaking change, no? The syntax extends SvelteComponent<...> { ... } ceases to work, right?
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That syntax was introduced in 3.30 but reverted in 3.31 because it introduced a breaking change. const a: typeof SvelteComponent = ASubclassOfSvelteComponent threw errors which it did not before. So yes, the syntax extends SvelteComponent<...> { ... } ceases to work, but it only worked for a few days / in 3.30.0.
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@dummdidumm it looks like |
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Ah. It was failing for me in #5746, but maybe that's because I bumped the eslint version which made it able to detect the unused variables |
const a: typeof SvelteComponent = ASubclassOfSvelteComponentthrows errors, which means existing usages are broken. To prevent this, the changes to a typedSvelteComponentin #5431 are reverted. Instead a newSvelteComponentTypedclass is added, which should be used for typing instead.