Changes to make actionlint usable when using it as a library

[hugo-syn]

I've added a constructor for RuleBase and changed error and errorf from private to public, otherwise It's not possible to create new rules. I hope that this is the best option, if not, how should we create new rules when using actionlint as a library ?

I also changed wait from private to public in process.go.

[rhysd]

What is the reason to make these APIs public? Especially, RuleBase is a base type for existing rules so it is unnecessarily public if you just use the rules. Do you make your own rules? I'd like to confirm your intention before review.

[hugo-syn]

Yes I would like to make my own rules

[rhysd]

Sounds nice. However, current API doesn't assume adding new rules. You need to reimplement Linter.check since rule instances are internally created in this method. This is strongly not recommended because it depends on implementation details which can be frequently modified.

Do you want some API to define additional rules?

For example:

opts := &LinterOptions {
    AdditionalRules: func() []Rule {
        return []Rule {
            NewYourOwnRule(),
        }
    }
}

linter = NewLinter(os.Stdout, opts)
linter.LintFiles("/path/to/dir", nil)

[hugo-syn]

I was actually reimplementing my own Linter to run my custom rules, because I don't want all the rules, so I just need to access the RuleBase and the methods error and errorf to create new rules

[rhysd]

OK. But please note that you can filter out errors from specific rules by -ignore.

[rhysd]

@hugo-syn I added OnRulesCreated hook API at 655d745. Note that now NewRuleBase returns RuleBase instead of *RuleBase since it is more useful for emebdding.

You can add/remove rules without reimplementing check method.

o := &LinterOptions{
    OnRulesCreated: func(rules []Rule) []Rule {
        // Remove 'runner-label' rule
        for i, r := range rules {
            if r.Name() == "runner-label" {
                rules = append(rules[:i], rules[i+1:]...)
                break
            }
        }
        // Add your own rule
        rules = append(rules, NewYourOwnRule())
        return rules
    },
}

So you no longer need to reimplement Linter.check only for adding/removing rules. With this API, can the ConcurrentProcess API be back to private since you no longer need to call NewRuleShellcheck by yourself?

I'd like to keep the API private since it is an implementation detail and can be updated on patch releases.

[hugo-syn]

Sounds nice, I think that I don't need to re-implement my linter now, thanks :)

[rhysd]

Great. Thank you for confirming that. I'll revert ConcurrentProcess to concurrentProcess