> The problem is that I can't declare the variable and set it's value as part of the same operation.

Care to elaborate? Consider the following:

    var foo = func() struct{ Bar int } {
        if os.Getenv("BAR") == "1" {
	    return struct{ Bar int }{1}
	}
	return struct{ Bar int }{2}
    }()

Is there a case where the foo variable can be assigned to something other than one of the two conditional-dependent values?