text/template: Why is there no support for "kebab-case" template variables?

[kostyay]

Hi
Is there a particular reason template variables can't contain dashes?

I'm aware of the index function. Just wondering why not support templates with kebab case directly using the prettier syntax.

The fix seems pretty simple in
template/parse/lex.go

// isAlphaNumeric reports whether r is an alphabetic, digit, or underscore.
func isAlphaNumeric(r rune) bool {
	return r == '_' || unicode.IsLetter(r) || unicode.IsDigit(r) || r == '-'
}

What side effects can this change have?
Thanks.

What version of Go are you using (go version)?

$ go version
1.16

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env

What did you do?

https://play.golang.org/p/NT4dgt0abWi

package main

import (
	"text/template"
	"os"
)

func main() {

	vals := map[string]string{"hello-world": "world!"}

	tmpl, err := template.New("test").Parse("{{ .hello-world }} items")
	if err != nil { panic(err) }
	err = tmpl.Execute(os.Stdout, vals)
	if err != nil { panic(err) }
}

What did you expect to see?

world! items

What did you see instead?

panic: template: test:1: bad character U+002D '-'

[mvdan]

Identifiers (names) in Go can only contain alphanumeric characters and underscores; it seems sane to have the same restriction on text/template. It is a different syntax, but it's still aimed at being Go-like.

[gopherbot]

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