Migrate CLI Package From Yargs To Citty

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Introduction

As a developer, you're likely familiar with the importance of a well-structured and maintainable command-line interface (CLI) package. In this article, we'll explore the process of migrating a CLI package from the popular yargs library to the modern and lightweight citty library. By the end of this guide, you'll have a clear understanding of the benefits and implementation details of this migration.

Why Migrate to Citty?

Better TypeScript Integration with Improved Type Safety

Citty is designed with TypeScript in mind, providing improved type safety and better integration with the language. This means that you can take advantage of TypeScript's powerful type system to ensure that your code is correct and maintainable.

More Modular and Composable Command Structure

Citty's API is designed to be more modular and composable, making it easier to create complex command structures. This means that you can break down your commands into smaller, reusable components, making your code more maintainable and easier to understand.

Lighter Dependencies for Improved Performance

Citty has a smaller dependency footprint compared to yargs, which means that your CLI package will be faster and more efficient. This is especially important for large-scale applications where performance is critical.

Enhanced Developer Experience with Modern API Design

Citty's API is designed to be more intuitive and easier to use, providing a better developer experience. This means that you can focus on building your CLI package without getting bogged down in complex configuration and setup.

Better Maintainability

Citty's design and architecture are focused on making it easier to maintain and update your CLI package. This means that you can make changes and updates without breaking existing functionality or introducing new bugs.

Migration Steps

Step 1: Add Citty as a Dependency

To start the migration process, you'll need to add citty as a dependency in your project. You can do this by running the following command:

npm install citty

Step 2: Create a New Command Structure Using Citty's defineCommand

Once you've added citty as a dependency, you can start creating a new command structure using the defineCommand method. This method allows you to define a new command with its own set of options and arguments.

const citty = require('citty');

citty.defineCommand('my-command', {
  description: 'My command',
  options: [
    {
      name: 'option1',
      type: 'string',
      description: 'Option 1',
    },
    {
      name: 'option2',
      type: 'boolean',
      description: 'Option 2',
    },
  ],
});

Step 3: Convert Shared Options to Citty's Argument Format

Once you've defined your new command structure, you'll need to convert any shared options to citty's argument format. This involves using the arg method to define a new argument with its own set of options and values.

const citty = require('citty');

citty.arg('option1', {
  type: 'string',
  description: 'Option 1',
});

citty.arg('option2', {
  type: 'boolean',
  description: 'Option 2',
});

Step 4: Implement Each Command Using Citty's API

Once you've converted your shared options to citty's argument format, you can start implementing each command using citty's API. This involves using the command method to define a new command with its own set of options and arguments.

const citty = require('citty');

citty.command('my-command', {
  description: 'My command',
  options: [
    {
      name: 'option1',
      type: 'string',
      description: 'Option 1',
    },
    {
      name: 'option2',
      type: 'boolean',
      description: 'Option 2',
    },
  ],
  handler: (args) => {
    console.log(`Option 1: ${args.option1}`);
    console.log(`Option 2: ${args.option2}`);
  },
});

Step 5: Update Custom Command Loading Logic

Once you've implemented each command using citty's API, you'll need to update your custom command loading logic to use citty's loadCommand method. This method allows you to load a command from a file or module.

const citty = require('citty');

citty.loadCommand('my-command', './commands/my-command.js');

Step 6: Ensure Backward Compatibility for All Command Options

Once you've updated your custom command loading logic, you'll need to ensure that all command options are backward compatible. This involves using citty's backwardCompatibility method to ensure that all options are correctly converted.

const citty = require('citty');

citty.backwardCompatibility({
  options: [
    {
      name: 'option1',
      type: 'string',
      description: 'Option 1',
    },
    {
      name: 'option2',
      type: 'boolean',
      description: 'Option 2',
    },
  ],
});

Step 7: Test Thoroughly with Both Implementations

Once you've ensured backward compatibility for all command options, you'll need to test thoroughly with both implementations. This involves using citty's test method to run a series of tests against both the yargs and citty implementations.

const citty = require('citty');

citty.test({
  yargs: true,
  citty: true,
});

Step 8: Switch to Citty Implementation by Default

Once you've tested thoroughly with both implementations, you can switch to the citty implementation by default. This involves updating your CLI package to use citty's API instead of yargs.

const citty = require('citty');

citty.defineCommand('my-command', {
  description: 'My command',
  options: [
    {
      name: 'option1',
      type: 'string',
      description: 'Option 1',
    },
    {
      name: 'option2',
      type: 'boolean',
      description: 'Option 2',
    },
  ],
});

Step 9: Remove Yargs Implementation When Stable

Once you've switched to the citty implementation by default, you can remove the yargs implementation when stable. This involves updating your CLI package to use citty's API exclusively.

const citty = require('citty');

citty.defineCommand('my-command', {
  description: 'My command',
  options: [
    {
      name: 'option1',
      type: 'string',
      description: 'Option 1',
    },
    {
      name: 'option2',
      type: 'boolean',
      description: 'Option 2',
    },
  ],
});

Implementation Details

A detailed migration plan has been prepared that outlines the specific steps and code changes required. The migration will be performed incrementally to ensure stability and backward compatibility.

Related

Introduction

In our previous article, we explored the process of migrating a CLI package from the popular yargs library to the modern and lightweight citty library. In this article, we'll answer some frequently asked questions about the migration process.

Q: What are the benefits of migrating to Citty?

A: The benefits of migrating to Citty include:

  • Better TypeScript integration with improved type safety
  • More modular and composable command structure
  • Lighter dependencies for improved performance
  • Enhanced developer experience with modern API design
  • Better maintainability

Q: How do I add Citty as a dependency?

A: To add Citty as a dependency, you can run the following command:

npm install citty

Q: What is the difference between Citty's defineCommand and arg methods?

A: The defineCommand method is used to define a new command with its own set of options and arguments. The arg method is used to define a new argument with its own set of options and values.

Q: How do I ensure backward compatibility for all command options?

A: To ensure backward compatibility for all command options, you can use Citty's backwardCompatibility method. This method allows you to specify a set of options that should be preserved in the new implementation.

Q: Can I use Citty with other libraries and frameworks?

A: Yes, Citty can be used with other libraries and frameworks. Citty is designed to be flexible and adaptable, making it easy to integrate with other tools and technologies.

Q: How do I test my CLI package with Citty?

A: To test your CLI package with Citty, you can use Citty's test method. This method allows you to run a series of tests against both the yargs and Citty implementations.

Q: What is the best way to handle errors and exceptions in Citty?

A: The best way to handle errors and exceptions in Citty is to use Citty's built-in error handling mechanisms. These mechanisms allow you to catch and handle errors in a centralized and consistent way.

Q: Can I customize the behavior of Citty?

A: Yes, Citty can be customized to meet the needs of your specific use case. Citty provides a range of options and settings that can be used to customize its behavior.

Q: How do I get started with Citty?

A: To get started with Citty, you can start by reading the Citty documentation and exploring the Citty API. You can also join the Citty community and ask questions to get help and support.

Q: What is the future of Citty?

A: The future of Citty is bright! Citty is a rapidly evolving library that is designed to meet the needs of modern CLI development. We are committed to continuing to improve and expand Citty to make it the best CLI library available.

Conclusion

In this article, we've answered some frequently asked questions about migrating a CLI package from yargs to Citty. We hope that this information has been helpful in your journey to migrate to Citty. If you have any further questions or need help with your migration, please don't hesitate to reach out to the Citty community.

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