Golang：如何使用TYPE声明返回的变量？

Question

In GO, how do I declare the returned variables of a function WITH TYPE ?

e.g. I have this code

dat, err := ioutil.ReadFile("/tmp/dat")
check(err)
fmt.Print(string(dat))

but what I want is this:

var dat []byte, err error := ioutil.ReadFile("/tmp/dat")
check(err)
fmt.Print(string(dat))

However, no matter how I try, I only get this output

syntax error: unexpected comma, expecting semicolon or newline or }

I'm working without IDE, and as the number of variables increases, it's really idiotic to have to keep all the return values's types in short-term memory... let alone if somebody else has to read the code.

How can I declare the returned tuple WITH type ?

Answer 1

That's because you're using := in your assignment there and that is a convenience syntax to declare and assign. It makes it so you don't have to provide the type, I assume the compiler just implies it by what is returned/whatever types come from the right hand side. Instead you need to do this;

var dat []byte
var err error

dat, err = ioutil.ReadFile("/tmp/dat")

But no one does this because dat, err := ioutil.ReadFile("/tmp/dat") is such a cleaner syntax.