error thought

gistfile1.txt

package main

import (
	"fmt"
)

type ErrorCode struct {
	code int
	next *ErrorCode
}

var (
	ErrorBadType ErrorCode = ErrorCode{1, nil}
)

func (ec *ErrorCode) String() string {
	res := "{"
	for ; ec != nil; ec = ec.next {
		if len(res) > 1 {
			res += ", "
		}
		res += fmt.Sprintf("[ %d ]", ec.code)
	}
	res = res + " }"
	return res
}

func (ec *ErrorCode) IsA(c ErrorCode) bool {
	return ec.Contains(c)
}

func (ec *ErrorCode) Contains(c ErrorCode) bool {
	for ; ec != nil; ec = ec.next {
		if ec.code == c.code {
			return true
		}
	}
	return false
}

func (ec *ErrorCode) Add(c ErrorCode) *ErrorCode {
	top := ec
	if top == nil {
		return &ErrorCode{c.code, c.next}
	}

	for ; ec.next != nil; ec = ec.next {
	}
	ec.next = &ErrorCode{c.code, c.next}

	return top
}

func foo() ErrorCode {
	return ErrorBadType
}

func main() {
	e := foo()
	fmt.Printf("e: %q\n", e.String())

	e.Add(foo())
	fmt.Printf("e: %q\n", e.String())

	fmt.Printf("isA: %q\n", e.IsA(ErrorBadType))

	fmt.Printf("==: %q\n", e == ErrorBadType)
}