cybercyst/go
1
0
Fork 0
mirror of https://github.com/golang/go.git synced 2025-05-05 15:43:04 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

text/template: provide example of overwriting template func after parse

Browse Source 
This example illustrates how to overwrite a template function after parsing a template.

This example is intended to clarify the point made in the template.Funcs docstring
that "[i]t is legal to overwrite elements of the map."

Change-Id: Ibded05974d580c54a24fcc16687fd52ce21133ff
GitHub-Last-Rev: ef19a221ab44f47695c27b3114281112231a1b42
GitHub-Pull-Request: golang/go#72094
Reviewed-on: https://go-review.googlesource.com/c/go/+/654416
Reviewed-by: Junyang Shao <shaojunyang@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
This commit is contained in:
rorycl 2025-03-04 22:47:17 +00:00 committed by Gopher Robot
parent 2e6cbab1c8
commit 2c16041423
1 changed files with 44 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
src/text/template/examplefunc_test.go
View File

@ -52,3 +52,47 @@ Output 2: {{printf "%q" . | title}}
// Output 1: "The Go Programming Language"
// Output 2: "The Go Programming Language"
}
// This example demonstrates registering two custom template functions
// and how to overwite one of the functions after the template has been
// parsed. Overwriting can be used, for example, to alter the operation
// of cloned templates.
func ExampleTemplate_funcs() {
// Define a simple template to test the functions.
const tmpl = `{{ . | lower | repeat }}`
// Define the template funcMap with two functions.
var funcMap = template.FuncMap{
"lower": strings.ToLower,
"repeat": func(s string) string { return strings.Repeat(s, 2) },
}
// Define a New template, add the funcMap using Funcs and then Parse
// the template.
parsedTmpl, err := template.New("t").Funcs(funcMap).Parse(tmpl)
if err != nil {
log.Fatal(err)
}
if err := parsedTmpl.Execute(os.Stdout, "ABC\n"); err != nil {
log.Fatal(err)
}
// [Funcs] must be called before a template is parsed to add
// functions to the template. [Funcs] can also be used after a
// template is parsed to overwrite template functions.
//
// Here the function identified by "repeat" is overwritten.
parsedTmpl.Funcs(template.FuncMap{
"repeat": func(s string) string { return strings.Repeat(s, 3) },
})
if err := parsedTmpl.Execute(os.Stdout, "DEF\n"); err != nil {
log.Fatal(err)
}
// Output:
// abc
// abc
// def
// def
// def
}