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82 lines
2.6 KiB
Markdown
82 lines
2.6 KiB
Markdown
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# Sprig: Template functions for Go templates
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[](https://masterminds.github.io/stability/sustained.html)
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[](https://travis-ci.org/Masterminds/sprig)
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The Go language comes with a [built-in template
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language](http://golang.org/pkg/text/template/), but not
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very many template functions. This library provides a group of commonly
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used template functions.
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It is inspired by the template functions found in
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[Twig](http://twig.sensiolabs.org/documentation) and also in various
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JavaScript libraries, such as [underscore.js](http://underscorejs.org/).
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## Usage
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Template developers can read the [Sprig function documentation](http://masterminds.github.io/sprig/) to
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learn about the >100 template functions available.
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For Go developers wishing to include Sprig as a library in their programs,
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API documentation is available [at GoDoc.org](http://godoc.org/github.com/Masterminds/sprig), but
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read on for standard usage.
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### Load the Sprig library
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To load the Sprig `FuncMap`:
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```go
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import (
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"github.com/Masterminds/sprig"
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"html/template"
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)
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// This example illustrates that the FuncMap *must* be set before the
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// templates themselves are loaded.
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tpl := template.Must(
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template.New("base").Funcs(sprig.FuncMap()).ParseGlob("*.html")
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)
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```
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### Call the functions inside of templates
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By convention, all functions are lowercase. This seems to follow the Go
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idiom for template functions (as opposed to template methods, which are
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TitleCase).
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Example:
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```
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{{ "hello!" | upper | repeat 5 }}
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```
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Produces:
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```
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HELLO!HELLO!HELLO!HELLO!HELLO!
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```
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## Principles:
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The following principles were used in deciding on which functions to add, and
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determining how to implement them.
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- Template functions should be used to build layout. Therefore, the following
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types of operations are within the domain of template functions:
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- Formatting
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- Layout
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- Simple type conversions
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- Utilities that assist in handling common formatting and layout needs (e.g. arithmetic)
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- Template functions should not return errors unless there is no way to print
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a sensible value. For example, converting a string to an integer should not
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produce an error if conversion fails. Instead, it should display a default
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value that can be displayed.
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- Simple math is necessary for grid layouts, pagers, and so on. Complex math
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(anything other than arithmetic) should be done outside of templates.
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- Template functions only deal with the data passed into them. They never retrieve
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data from a source.
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- Finally, do not override core Go template functions.
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