faq.md

Babel

At first we did not support Babel because they drop support for decorators (year ago, by the time of writing)... nowadays they provide support under babel 6 babel-plugin-transform-decorators-legacy or babel 7 @babel/plugin-proposal-decorators

I would recommend babel 7 with following .babelrc setup:

{
  "presets": [["@babel/preset-env", {
    "targets": {
        <<<any es6 target>>>
      }
    }], "@babel/preset-stage-2"],
  "plugins": [
    ["@babel/plugin-proposal-decorators", { "legacy": true }]
  ]
}

Motivation

Typescript

This is the minimal tsconfig.json.

{
    "compilerOptions": {
      "target": "es6",
      "experimentalDecorators": true
    }
}

Do not reassign methods or use decorators on arrow functions (i.e.: public something = () => {})

kaop-ts uses metadata properties inside methods or classes. If you alter that references by reasignment you'll mess Advice call stack.

Useful Tips

Join points decorators can be stacked and used sync or asynchronously.

Advices share target context, arguments, result, or any property you bind to this. But keep in mind that it will only survive during the call stack, then the only thing preserved is the target instance.

You can prevent main method execution by calling meta.prevent.

Some contexts or metadata may be accessible in several cases. For example: trying to modify method arguments at after join point doesn't have any sense. Maybe for communication purposes between advices.