Result

Result is a Go library that only provides a simple Result object, that is intended to replace conventional value-error pair returning.

Motivation

It is too easy to bypass error checking, which can lead to a nil reference panic or even worse to an undefined behaviour when the result of a function is returned by value, rather than a reference.

Usage

Conceptually, there are two conditions of a result: fake and real.

A fake result contains no value, and has an error. If your try to unwrap a fake result via the Value method, you will get a runtime panic. To check for an error you should first check the result via Error method, and see if it returns an error or a nil.

On the other hand a real result does contain a value, and has no error and can be safely unwrapped via the Value method.

Warning

Making a result directly via struct construction (i.e result.Result[any]{}) is unsupported and leads to undefined behaviour.

package main

import (
    "math/rand"

    "github.com/widetape/result"
)

func realResult() result.Result[int] {
    return result.Real(rand.Int())
}

func fakeResult() result.Result[int] {
    return result.Fake(errors.New("no int this time"))
}

func main() {
    real := realResult()
    if err := real.Error(); err != nil {
        panic(err) // <- this won't happen
    }
    println(real.Value()) // this will output a random integer.

    fake := fakeResult()
    println(fake.Value()) // panic! one cannot simply use a fake result's non-existent value.
    if err := fake.Error(); err != nil {
        println(err.Error()) // "no int this time"
    }
}