Help Using Funcs

[jamesgoodhouse]

I have setup a LocalizeConfig to include a Funcs definition. However, it's unclear how those are to be used. When I attempt to use a function I've defined in a template, I get a panic saying it is not defined.

Is there additional documentation on how one uses these?

[nicksnyder]

There isn't any additional documentation right now. The Funcs you provide are forwarded to .Funcs on text/template here. It is definitely possible there is a bug; I just realized there are no unit tests to cover this. If you are seeing a panic can you post a stack trace?

[patgrasso]

@nicksnyder I've also encountered a panic when running goi18n extract with Funcs provided. I haven't delved too deep into why it happens, but it appears to stem from this line in extractStringLiteral(). An instance of *ast.Ident's Obj field is used without a nil pointer check.

Here's a simple case that triggers the problem.

// funcs.go
package bug

import "text/template"

var Funcs = template.FuncMap{
	"noop": func(x interface{}) interface{} {
		return x
	},
}

// render.go
package bug

import "github.com/nicksnyder/go-i18n/v2/i18n"

func Render(m *i18n.Message) {
	l := i18n.NewLocalizer(nil, "en")
	l.Localize(&i18n.LocalizeConfig{
		DefaultMessage: m,
		Funcs: Funcs,        // <- note, Funcs is define in another file
	})
}

However, it works just fine if I define Funcs in the same file as where it's used.

// render.go
package bug

import (
	"github.com/nicksnyder/go-i18n/v2/i18n"
	"text/template"
)

var Funcs = template.FuncMap{
	"noop": func(x interface{}) interface{} {
		return x
	},
}

func Render(m *i18n.Message) {
	l := i18n.NewLocalizer(nil, "en")
	l.Localize(&i18n.LocalizeConfig{
		DefaultMessage: m,
		Funcs: Funcs,
	})
}

It seems like a reasonable solution might be to just return from extractStringLiteral if the identifier's Obj is nil.

Would be happy to open a PR with a fix & a corresponding test case if you agree!

[patgrasso]

Also, I'm not 100% sure if this problem is the same as the one jamesgoodhouse is seeing. It seems like it might be, but if you want me to open a separate issue for this let me know.

[nicksnyder]

@patgrasso Looks like you found a bug, thanks! Yes please open a PR if you can to fix this (and include tests).