Conditionally Define a Variable

In javascript we can do this:

var x string = expr1 || expr2

If expr1 is not undefined, it will be copied to x, if it is undefined, expr2 will be copied to x. In go, we can use:

if expr1 == "" { var string x = expr1 } else { var string x = expr2 }

Is there are shorthand for this? If not, why?

I don't know about the "why" however you can always use this :

var a []string = expr1

if a == nil {
    a = expr2
}

> The Go Programming Language Specification
>
> Declarations and scope
>
> A declaration binds a non-blank identifier to a constant, type,
> variable, function, label, or package. Every identifier in a program
> must be declared.
>
> The zero value
>
> When memory is allocated to store a value, either through a
> declaration or a call of make or new, and no explicit initialization
> is provided, the memory is given a default initialization. Each
> element of such a value is set to the zero value for its type: false
> for booleans, 0 for integers, 0.0 for floats, "" for strings, and nil
> for pointers, functions, interfaces, slices, channels, and maps.

> Type system
>
> Static type-checking
>
> Dynamic type-checking

Go is a statically typed language. All variables must be declared at compile time and they have an well-defined initial value. JavaScript is a dynamically typed language. Variables are declared at run time. Therefore, the JavaScript construct makes no sense in Go.