Type Inspection In Go


2 minute read


Since it seems to be the vogue inevitability for JS/Node engineers to dabble in Go, I am inevitably, well, dabbling in Go.

My experience with the language so far has been an extremely pleasant one. In many ways it has been like sipping a surprisingly good cup of espresso that I hadn’t tried before. Furthermore, the approach it takes to extending functionality has been incredible; it’s composition over inheritance, but built into the language.

typeof in Go

One thing I ran into when using Go for the donation pages server for Charityware was checking to see what type I was dealing with at various points in my program. I’m more used to the rampant type coercion of JavaScript, so I reached for some equivalent of typeof to inspect things. typeof is, of course, a reserved word in JavaScript that you get globally provided. In Go, reflection is its own package and it’s not hard to use. To inspect the type of a given Go is statically typed, just pull in the reflect package and use its TypeOf method:

run it here

package main

import (
	"fmt"
	"reflect"
)

type Foo struct {
	a string
	b string
}


func main() {
	fooInt := 2.10000
	fmt.Println("FooInt has type ", reflect.TypeOf(fooInt))
	
	zip := "zip"
	fmt.Println("zip has type ", reflect.TypeOf(zip))
	
	compositeType := Foo{"a", "b"}
	fmt.Println("Foo has type ", reflect.TypeOf(compositeType))
}

There’s lots more to reflection and typing in Go, but I won’t cover it here. See the in-depth post at the Golang official blog, The Laws of Reflection.

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