packer-cn/common/template/funcs.go

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package template
import (
"log"
"sync"
)
// DeprecatedTemplateFunc wraps a template func to warn users that it's
// deprecated. The deprecation warning is called only once.
func DeprecatedTemplateFunc(funcName, useInstead string, deprecated func(string) string) func(string) string {
once := sync.Once{}
return func(in string) string {
once.Do(func() {
log.Printf("[WARN]: the `%s` template func is deprecated, please use %s instead",
funcName, useInstead)
})
return deprecated(in)
}
}