导入库上的golang未定义函数调用

Question

I've imported

_ "github.com/mitchellh/mapstructure"

Into a project of mine. However i'm not able to utilize the Decode function included in that library in order to convert a map interface to struct:

var result Person
err := Decode(input, &result)
if err != nil {
    panic(err)
}

This basic call returns "undefined: Decode" error. Is there anything else to be done besides the import?

Thanks in advance!

Answer 1

If you import a package with _ as first argument, you cannot use any function or type of that package. _ means that you are importing the package only for its secondary effects of calling the init() functions.

In addition, you need to use the package name before the function, mapstructure.Decode in this case.

Alternatively, as pointed out by Ainar-G, you may use "." instead of _ when importing the package. This way you will be importing the names to the "default" namespace, allowing to use Decode directly. However, this is not recommended because you are polluting the namespace with other names and there may be conflicts, now or in the future.