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Clarify data type returned by partial and partialCached
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@ -1,7 +1,7 @@
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---
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title: Go template functions
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title: Go template functions, operators, and statements
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linkTitle: go template
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description: Template functions and statements provided by Go's text/template package.
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description: Template functions, operators, and statements provided by Go's text/template package.
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categories: []
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keywords: []
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menu:
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@ -9,6 +9,6 @@ menu:
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parent: functions
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---
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These are the statements, operators, and functions provided by Go's [text/template] package.
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These are the functions, operators, and statements provided by Go's [text/template] package.
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[text/template]: https://pkg.go.dev/text/template
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110
content/en/functions/go-template/return.md
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110
content/en/functions/go-template/return.md
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---
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title: return
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description: Used within partial templates, terminates template execution and returns the given value, if any.
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categories: []
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keywords: []
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action:
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aliases: []
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related:
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- functions/partials/Include
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- functions/partials/IncludeCached
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returnType: any
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signatures: ['return [VALUE]']
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toc: true
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---
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The `return` statement is a custom addition to Go's [text/template] package. Used within partial templates, the `return` statement terminates template execution and returns the given value, if any.
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The returned value may be of any data type including, but not limited to, [`bool`], [`float`], [`int`], [`map`], [`resource`], [`slice`], and [`string`].
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A `return` statement without a value returns an empty string of type `template.HTML`.
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[`bool`]: /getting-started/glossary/#bool
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[`float`]: /getting-started/glossary/#float
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[`int`]: /getting-started/glossary/#int
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[`map`]: /getting-started/glossary/#map
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[`resource`]: /getting-started/glossary/#resource
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[`slice`]: /getting-started/glossary/#slice
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[`string`]: /getting-started/glossary/#string
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[text/template]: https://pkg.go.dev/text/template
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{{% note %}}
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Unlike `return` statements in other languages, Hugo executes the first occurence of the `return` statement regardless of its position within logical blocks. See [usage](#usage) notes below.
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{{% /note %}}
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## Example
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By way of example, let's create a partial template that _renders_ HTML, describing whether the given number is odd or even:
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{{< code file="layouts/partials/odd-or-even.html" >}}
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{{ if math.ModBool . 2 }}
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<p>{{ . }} is even</p>
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{{ else }}
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<p>{{ . }} is odd</p>
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{{ end }}
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{{< /code >}}
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When called, the partial renders HTML:
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```go-html-template
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{{ partial "odd-or-even.html" 42 }} → <p>42 is even</p>
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```
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Instead of rendering HTML, let's create a partial that _returns_ a boolean value, reporting whether the given number is even:
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{{< code file="layouts/partials/is-even.html" >}}
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{{ return math.ModBool . 2 }}
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{{< /code >}}
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With this template:
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```go-html-template
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{{ $number := 42 }}
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{{ if partial "is-even.html" $number }}
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<p>{{ $number }} is even</p>
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{{ else }}
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<p>{{ $number }} is odd</p>
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{{ end }}
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```
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Hugo renders:
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```html
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<p>42 is even</p>
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```
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See additional examples in the [partial templates] section.
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[partial templates]: /templates/partials/#returning-a-value-from-a-partial
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## Usage
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{{% note %}}
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Unlike `return` statements in other languages, Hugo executes the first occurence of the `return` statement regardless of its position within logical blocks
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{{% /note %}}
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A partial that returns a value must contain only one `return` statement, placed at the end of the template.
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For example:
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{{< code file="layouts/partials/is-even.html" >}}
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{{ $result := false }}
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{{ if math.ModBool . 2 }}
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{{ $result = "even" }}
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{{ else }}
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{{ $result = "odd" }}
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{{ end }}
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{{ return $result }}
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{{< /code >}}
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{{% note %}}
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The construct below is incorrect; it contains more than one `return` statement.
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{{% /note %}}
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{{< code file="layouts/partials/do-not-do-this.html" >}}
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{{ if math.ModBool . 2 }}
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{{ return "even" }}
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{{ else }}
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{{ return "odd" }}
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{{ end }}
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{{< /code >}}
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@ -1,19 +1,24 @@
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---
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title: partials.Include
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description: Executes the given partial template, optionally passing context. If the partial contains a return statement, returns that value, else returns the rendered output.
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description: Executes the given partial template, optionally passing context. If the partial template contains a return statement, returns the given value, else returns the rendered output.
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categories: []
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keywords: []
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action:
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aliases: [partial]
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related:
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- functions/go-template/template
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- functions/go-template/return
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- functions/partials/IncludeCached
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- functions/go-template/template
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- methods/page/Render
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returnType: any
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signatures: ['partials.Include NAME [CONTEXT]']
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aliases: [/functions/partial]
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---
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Without a [`return`] statement, the `partial` function returns a string of type `template.HTML`. With a `return` statement, the `partial` function can return any data type.
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[`return`]: /functions/go-template/return
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In this example we have three partial templates:
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```text
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@ -60,4 +65,21 @@ Then, within the partial template:
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<p>{{ .name }} is majoring in {{ .major }}. Their grade point average is {{ .gpa }}.</p>
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```
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To return a value from a partial template, it must contain only one `return` statement, placed at the end of the template:
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```go-html-template
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{{ $result := false }}
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{{ if math.ModBool . 2 }}
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{{ $result = "even" }}
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{{ else }}
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{{ $result = "odd" }}
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{{ end }}
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{{ return $result }}
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```
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See [details][`return`].
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[`return`]: /functions/go-template/return
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[breadcrumb navigation]: /content-management/sections/#ancestors-and-descendants
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[details]: /functions/go-template/return
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@ -1,13 +1,14 @@
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---
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title: partials.IncludeCached
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description: Executes the given template and caches the result, optionally passing context. If the partial contains a return statement, returns that value, else returns the rendered output.
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description: Executes the given template and caches the result, optionally passing context. If the partial template contains a return statement, returns teh given value, else returns the rendered output.
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categories: []
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keywords: []
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action:
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aliases: [partialCached]
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related:
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- functions/go-template/template
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- functions/go-template/return
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- functions/partials/Include
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- functions/go-template/template
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- methods/page/Render
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returnType: any
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signatures: ['partials.IncludeCached LAYOUT CONTEXT [VARIANT...]']
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@ -17,7 +18,11 @@ signatures:
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aliases: [/functions/partialcached]
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---
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The `partialCached` template function can offer significant performance gains for complex templates that don't need to be re-rendered on every invocation.
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Without a [`return`] statement, the `partialCached` function returns a string of type `template.HTML`. With a `return` statement, the `partialCached` function can return any data type.
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The `partialCached` function can offer significant performance gains for complex templates that don't need to be re-rendered on every invocation.
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{{% note %}}
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Each Site (or language) has its own `partialCached` cache, so each site will execute a partial once.
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@ -31,18 +36,32 @@ Here is the simplest usage:
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{{ partialCached "footer.html" . }}
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```
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You can also pass additional arguments to `partialCached` to create *variants* of the cached partial. For example, if you have a complex partial that should be identical when rendered for pages within the same section, you could use a variant based upon section so that the partial is only rendered once per section:
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Pass additional arguments to `partialCached` to create variants of the cached partial. For example, if you have a complex partial that should be identical when rendered for pages within the same section, use a variant based on section so that the partial is only rendered once per section:
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{{< code file=partial-cached-example.html >}}
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{{ partialCached "footer.html" . .Section }}
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{{< /code >}}
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If you need to pass additional arguments to create unique variants, you can pass as many variant arguments as you need:
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Pass additional arguments, of any data type, as needed to create unique variants:
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```go-html-template
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{{ partialCached "footer.html" . .Params.country .Params.province }}
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```
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Note that the variant arguments are not made available to the underlying partial template. They are only use to create a unique cache key. Since Hugo `0.61.0` you can use any object as cache key(s), not just strings.
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The variant arguments are not available to the underlying partial template; they are only used to create unique cache keys.
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See also [The Full Partial Series Part 1: Caching!](https://regisphilibert.com/blog/2019/12/hugo-partial-series-part-1-caching-with-partialcached/).
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To return a value from a partial template, it must contain only one `return` statement, placed at the end of the template:
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```go-html-template
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{{ $result := false }}
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{{ if math.ModBool . 2 }}
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{{ $result = "even" }}
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{{ else }}
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{{ $result = "odd" }}
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{{ end }}
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{{ return $result }}
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```
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See [details][`return`].
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[`return`]: /functions/go-template/return
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