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This guide explains how to create custom printers for BeDoc. Printers are responsible for transforming parsed documentation into specific output formats like Markdown, HTML, or any other format you need.

Printer Structure​

A BeDoc printer consists of two main parts:

  1. Meta Information: Defines the format and file extension. (required)
  2. Contract: Specifies the printer interface. (required)
  3. Parser Object: Implements the printer logic. (required)
  4. Hooks: Supports hook points for custom logic. (optional, external)

A printer action is contained in a JavaScript action file.

Here's the minimal structure for a BeDoc printer:

Printer​

{
  // Define meta information
  meta = {
    action: "print",          // required
    format: "wikitext",       // required
    documentExtension: ".md"  // You can add anything else your
                              // action needs, if you want to. 🤷🏻
  },

  /**
   * This is the setup function, called in advance of running the job.
   *
   * @param {object} setup An object containing utility objects exposed by BeDoc
   * @param {object} setup.log A logging utility provided by BeDoc
   */
  setup(setup) {
    ({ log: this.log } = setup)
  },

  /**
   * This is the action to print structured object to text.
   *
   * @param {object} module Data coming in from the printer
   * @param {string} module.file The file object representing the file
   *  being currently being processed
   * @param {object[]} module.moduleContent An array of objects containing
   *  function definitions prepared by the parser.
   * @returns {Promise<object>} The result of the print operations.
   */
  async run(module) {
    // Print the content and return a response
    const {file: {module: moduleName}, moduleContent} = module

    // You know what? No.
    const finalOutput =
      `${module.toUpperCase()} has to have the worst grammar ever. ` +
      `I refuse to print it.`

    return {
      status: "success",                                    // Required
      message: "File printed successfully. 😏",             // Optional
      destFile: `${moduleName}${this.documentExtension}`,   // Required
      destContent: finalOutput,                             // Required
    }
  }
}

Response Format​

The printer's run method must return a response object with the following structure:

Success​

To convey success and further information about the job, return a success object.

// Success response
{
  status: "success",
  destFile: string,    // Output filename (e.g., "module.md")
  content: string,     // Formatted documentation content
}

Warning​

To return no content, except a warning, you may return a warning object.

// Warning response
{
  status: "warning",
  warning: string,      // War
}

Error​

At the time of this writing, an error response is not required. You may simply throw(), and BeDoc will catch() it and report it.

Core Utilities​

The printer has access to certain of BeDoc's core utilities through object propagated during the setup() function.

  • Logging functions (debug, info, warn, error)

Hook Support​

Printers automatically support hooks, allowing users to modify the printing process. Hook points include:

  • start: Before printing begins
  • section_load: When a documentation section is loaded
  • enter: When entering a section
  • exit: When exiting a section
  • end: After printing completes

Example Implementation​

You can see examples of printer implementations on GitHub.

Best Practices​

  1. Error Handling: Always return appropriate error responses with detailed messages.

  2. Async Support: Make your printer async to handle large documents efficiently and support async hooks.

  3. Validation: Validate input content structure before processing.

  4. Content Structure: Keep your output well-organized and consistent with the format's conventions.

Testing Your Printer​

BeDoc provides multiple ways to test your printers:

  1. Mock Mode: Test using a local mock environment:

    bedoc --mock ./mock_dir -l javascript -f myformat -i test/*.js -o test/docs

  2. Direct File Usage: Test your printer file directly without installing:

    bedoc --printer ./my-printer.js -l javascript -i test/*.js -o test/docs
    # Or use the short form
    bedoc -P ./my-printer.js -l javascript -i test/*.js -o test/docs

These options allow you to rapidly iterate on your printer implementation without needing to package and install it first.

Publishing Your Printer​

When ready to publish, package your printer following BeDoc's naming and structure conventions:

{
  "name": "bedoc-myformat-printer",
  "version": "1.0.0",
  "type": "module",
  "description": "MyFormat printer for BeDoc",
  "bedoc": {
    "actions": [
      "./bedoc-myformat-printer.js"
    ]
  }
}

You can also package multiple printers together:

{
  "name": "bedoc-doc-printers",
  "version": "1.0.0",
  "type": "module",
  "description": "Documentation printers for BeDoc",
  "bedoc": {
    "actions": [
      "./bedoc-markdown-printer.js",
      "./bedoc-html-printer.js"
    ]
  }
}

This structure allows BeDoc to automatically discover and load your printer when installed.