textlint: allow to modify message for re-use rules

[azu]

We have changed context to frozen object in textlint 11

• https://textlint.github.io/blog/2018/07/22/textlint-11.html#developer-freeze-rule-s-context-508-https-githubcom-textlint-textlint-issues-508
• Freeze Context #527

This change make following hack error.

Issue: textlint-rule/textlint-rule-preset-google#35

✖ Error
Error while loading rule '@textlint-rule/preset-google/capitalization': Cannot assign to read only property 'report' of object '#<RuleContext>'

✖ Stack trace
TypeError: Error while loading rule '@textlint-rule/preset-google/capitalization': Cannot assign to read only property 'report' of object '#<RuleContext>'
    at Function.assign (<anonymous>)

        // overwrite report function
        return capitalizationReport(
            Object.assign(context, {
                report: (node, error) => {
                    error.message += "\n" + DocumentURL;
                    report(node, error);
                }
            }),
            options
        );

I think that it is corner case, but it is reasonable.

Purpose

A rule can re-use existing rule, but modify error message.

This is related with "Localize messages support #252"
Custom message support will resolve this issue.

Or, Should we provide overlay/proxy for context object?

const Proxy = require("textlint-rule-proxy");
const existingRule = require("textlint-rule-existing-rule");
export function rule(context){
   const proxyContext = Proxy.create(context, {
     report(node, error){
       error.message = "HI"
       // modify message and report it
       context.report(node, error);
     }
   });
   return existingRule(proxyContext);
}

Workaround

javascript - Creating new objects from frozen parent objects - Stack Overflow

Use Obejct.defineProperty for overwrite report function.

    const overlayContext = Object.create(context);
    Object.defineProperty(overlayContext, "report", {
        value: (node, error) => {
            error.message += "\nhttps://developers.google.com/style/exclamation-points";
            report(node, error);
        },
        enumerable: true,
        configurable: true,
        writable: true
    });

Related

• fix(capitalization): support textlint 11 textlint-rule/textlint-rule-preset-google#36
• Localize message support Localize messages support #252

[azu]

Related Note: I want to get file list that are linted from RuleContext.
A rule lint the reference of the document.
Currently, a rule does not get the reference of the document.
The file list will resolve this issue.

[azu]

Dead simple implementation: Use Proxy.

kernel.lintText(text, {
            ext: path.extname(filePath),
            filePath,
            rules: [
                {
                    ruleId: "file-size",
                    rule: fileSizeRule
                }
            ],
            plugins: [
                {
                    pluginId: "markdown",
                    plugin: markdown
                }
            ],
            contextProxyHandler: {
               // proxy handler
            }
        })

• Proxy - JavaScript | MDN