feat(createReusableTemplate): new function

packages/core/createReusableTemplate/index.md

@@ -0,0 +1,198 @@
+---
+category: Component
+outline: deep
+---
+
+# createReusableTemplate
+
+Define and reuse template inside the component scope.
+
+## Motivation
+
+It's common to have the need to reuse some part of the template. For example:
+
+```html
+<template>
+  <dialog v-if="showInDialog">
+    <!-- something complex -->
+  </dialog>
+  <div v-else>
+    <!-- something complex -->
+  </div>
+</template>
+```
+
+We'd like to reuse our code as much as possible. So normally we might need to extract those duplicated parts into a component. However, in a separated component you lose the ability to access the local bindings. Defining props and emits for them can be tedious sometime.
+
+So this function is made to provide a way for defining and reusing templates inside the component scope.
+
+## Usage
+
+In the previous example, we could refactor it to:
+
+```html
+<script setup>
+import { createReusableTemplate } from '@vueuse/core'
+
+const [DefineTemplate, ReuseTemplate] = createReusableTemplate()
+</script>
+
+<template>
+  <DefineTemplate>
+    <!-- something complex -->
+  </DefineTemplate>
+
+  <dialog v-if="showInDialog">
+    <ReuseTemplate />
+  </dialog>
+  <div v-else>
+    <ReuseTemplate />
+  </div>
+</template>
+```
+
+- `<DefineTemplate>` will register the template and renders nothing.
+- `<ReuseTemplate>` will render the template provided by `<DefineTemplate>`.
+- `<DefineTemplate>` must be used before `<ReuseTemplate>`.
+
+> **Note**: It's recommanded to extract as separate components whenever possible. Abusing this function might lead to bad practices for your codebase.
+
+### Passing Data
+
+You can also pass data to the template using slots:
+
+- Use `v-slot="..."` to access the data on `<DefineTemplate>`
+- Directly bind the data on `<ReuseTemplate>` to pass them to the template
+
+```html
+<script setup>
+import { createReusableTemplate} from '@vueuse/core'
+
+const [DefineTemplate, ReuseTemplate] = createReusableTemplate()
+</script>
+
+<template>
+  <DefineTemplate v-slot="{ data, msg, anything }">
+    <div>{{ data }} passed from usage</div>
+  </DefineTemplate>
+
+  <ReuseTemplate :data="data" msg="The first usage" />
+  <ReuseTemplate :data="anotherData" msg="The second usage" />
+  <ReuseTemplate v-bind="{ data: something, msg: 'The third' }" />
+</template>
+```
+
+### TypeScript Support
+
+`createReusableTemplate` accepts a generic type to provide type support for the data passed to the template:
+
+```html
+<script setup lang="ts">
+import { createReusableTemplate } from '@vueuse/core'
+
+// Comes with pair of `DefineTemplate` and `ReuseTemplate`
+const [DefineFoo, ReuseFoo] = createReusableTemplate<{ msg: string }>()
+
+// You can create multiple reusable templates
+const [DefineBar, ReuseBar] = createReusableTemplate<{ items: string[] }>()
+</script>
+
+<template>
+  <DefineFoo v-slot="{ msg }">
+    <!-- `msg` is typed as `string` -->
+    <div>Hello {{ msg.toUpperCase() }}</div>
+  </DefineFoo>
+
+  <ReuseFoo msg="World" />
+
+  <!-- @ts-expect-error Type Error! -->
+  <ReuseFoo :msg="1" />
+</template>
+```
+
+Optionally, if you are not a fan of array destructuring, the following usages are also legal:
+
+```html
+<script setup lang="ts">
+import { createReusableTemplate } from '@vueuse/core'
+
+const {
+  define: DefineFoo,
+  reuse: ReuseFoo,
+} = createReusableTemplate<{ msg: string }>()
+</script>
+
+<template>
+  <DefineFoo v-slot="{ msg }">
+    <div>Hello {{ msg.toUpperCase() }}</div>
+  </DefineFoo>
+
+  <ReuseFoo msg="World" />
+</template>
+```
+
+```html
+<script setup lang="ts">
+import { createReusableTemplate } from '@vueuse/core'
+
+const TemplateFoo = createReusableTemplate<{ msg: string }>()
+</script>
+
+<template>
+  <TemplateFoo.define v-slot="{ msg }">
+    <div>Hello {{ msg.toUpperCase() }}</div>
+  </TemplateFoo.define>
+
+  <TemplateFoo.reuse msg="World" />
+</template>
+```
+
+::: info
+Dot notation is not supported in Vue 2.
+:::
+
+### Passing Slots
+
+It's also possible to pass slots back from `<ReuseTemplate>`. You can access the slots on `<DefineTemplate>` from `$slots`:
+
+```html
+<script setup>
+import { createReusableTemplate } from '@vueuse/core'
+
+const [DefineTemplate, ReuseTemplate] = createReusableTemplate()
+</script>
+
+<template>
+  <DefineTemplate v-slot="{ $slots, otherProp }">
+    <div some-layout>
+      <!-- To render the slot -->
+      <component :is="$slots.default" />
+    </div>
+  </DefineTemplate>
+
+  <ReuseTemplate>
+    <div>Some content</div>
+  </ReuseTemplate>
+  <ReuseTemplate>
+    <div>Another content</div>
+  </ReuseTemplate>
+</template>
+```
+
+::: info
+Passing slots does not work in Vue 2.
+:::
+
+## References
+
+This function is migrated from [vue-reuse-template](https://github.com/antfu/vue-reuse-template).
+
+Existing Vue discussions/issues about reusing template:
+
+- [Discussion on Reusing Templates](https://github.com/vuejs/core/discussions/6898)
+
+Alternative Approaches:
+
+- [Vue Macros - `namedTemplate`](https://vue-macros.sxzz.moe/features/named-template.html)
+- [`unplugin-@vueuse/core`](https://github.com/liulinboyi/unplugin-@vueuse/core)
+

packages/core/createReusableTemplate/index.test.ts

@@ -0,0 +1,83 @@
+import { describe, expect, it } from 'vitest'
+import { mount } from '@vue/test-utils'
+import type { Slot } from 'vue-demi'
+import { Fragment, defineComponent, h, isVue2, renderSlot } from 'vue-demi'
+import { createReusableTemplate } from '.'
+
+describe.skipIf(isVue2)('createReusableTemplate', () => {
+  it('should work', () => {
+    const [DefineFoo, ReuseFoo] = createReusableTemplate()
+    const [DefineBar, ReuseBar] = createReusableTemplate()
+    const Zig = createReusableTemplate()
+
+    const wrapper = mount({
+      render() {
+        return h(Fragment, null, [
+          h(DefineFoo, () => ['Foo']),
+          h(ReuseFoo),
+
+          h(DefineBar, () => ['Bar']),
+          h(Zig.define, () => ['Zig']),
+          h(ReuseFoo),
+          h(ReuseBar),
+          h(Zig.reuse),
+        ])
+      },
+    })
+
+    expect(wrapper.text()).toBe('FooFooBarZig')
+  })
+
+  it('nested', () => {
+    const CompA = defineComponent((_, { slots }) => {
+      return () => renderSlot(slots, 'default')
+    })
+
+    const [DefineFoo, ReuseFoo] = createReusableTemplate()
+
+    const wrapper = mount({
+      render() {
+        return h(Fragment, null, [
+          h(DefineFoo, () => ['Foo']),
+          h(CompA, () => h(ReuseFoo)),
+        ])
+      },
+    })
+
+    expect(wrapper.text()).toBe('Foo')
+  })
+
+  it('props', () => {
+    const [DefineFoo, ReuseFoo] = createReusableTemplate<{ msg: string }>()
+
+    const wrapper = mount({
+      render() {
+        return h(Fragment, null, [
+          h(DefineFoo, ({ $slots, ...args }: any) => h('pre', JSON.stringify(args))),
+
+          h(ReuseFoo, { msg: 'Foo' }),
+          h(ReuseFoo, { msg: 'Bar' }),
+        ])
+      },
+    })
+
+    expect(wrapper.text()).toBe('{"msg":"Foo"}{"msg":"Bar"}')
+  })
+
+  it('slots', () => {
+    const [DefineFoo, ReuseFoo] = createReusableTemplate<{ msg: string }, { default: Slot }>()
+
+    const wrapper = mount({
+      render() {
+        return h(Fragment, null, [
+          h(DefineFoo, (args: any) => args.$slots.default?.()),
+
+          h(ReuseFoo, () => h('div', 'Goodbye')),
+          h(ReuseFoo, () => h('div', 'Hi')),
+        ])
+      },
+    })
+
+    expect(wrapper.text()).toBe('GoodbyeHi')
+  })
+})

packages/core/createReusableTemplate/index.ts

@@ -0,0 +1,57 @@
+import type { DefineComponent, Slot } from 'vue-demi'
+import { defineComponent } from 'vue-demi'
+import { __onlyVue27Plus, makeDestructurable } from '@vueuse/shared'
+
+export type DefineTemplateComponent<
+  Bindings extends object,
+  Slots extends Record<string, Slot | undefined>,
+  Props = {},
+> = DefineComponent<Props> & {
+  new(): { $slots: { default(_: Bindings & { $slots: Slots }): any } }
+}
+
+export type ReuseTemplateComponent<
+  Bindings extends object,
+  Slots extends Record<string, Slot | undefined>,
+> = DefineComponent<Bindings> & {
+  new(): { $slots: Slots }
+}
+
+/**
+ * This function creates `define` and `reuse` components in pair,
+ * It also allow to pass a generic to bind with type.
+ *
+ * @see https://vueuse.org/createReusableTemplate
+ */
+export function createReusableTemplate<
+  Bindings extends object,
+  Slots extends Record<string, Slot | undefined> = Record<string, Slot | undefined>,
+>(name?: string) {
+  __onlyVue27Plus()
+
+  let render: Slot | undefined
+
+  const define = defineComponent({
+    setup(_, { slots }) {
+      return () => {
+        render = slots.default
+      }
+    },
+  }) as DefineTemplateComponent<Bindings, Slots>
+
+  const reuse = defineComponent({
+    inheritAttrs: false,
+    setup(_, { attrs, slots }) {
+      return () => {
+        if (!render && process.env.NODE_ENV !== 'production')
+          throw new Error(`[VueUse] Failed to find the definition of template${name ? ` "${name}"` : ''}`)
+        return render?.({ ...attrs, $slots: slots })
+      }
+    },
+  }) as ReuseTemplateComponent<Bindings, Slots>
+
+  return makeDestructurable(
+    { define, reuse },
+    [define, reuse] as const,
+  )
+}

packages/core/index.ts

@@ -1,5 +1,6 @@
 export * from './computedAsync'
 export * from './computedInject'
+export * from './createReusableTemplate'
 export * from './createUnrefFn'
 export * from './onClickOutside'
 export * from './onKeyStroke'