65 lines
2.8 KiB
Markdown
65 lines
2.8 KiB
Markdown
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# extra-typings for commander
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[](https://www.npmjs.org/package/@commander-js/extra-typings)
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[](https://npmcharts.com/compare/@commander-js/extra-typings?minimal=true)
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This package offers experimental TypeScript typings for `commander` which infer strong types for:
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- all the parameters of the action handler, including the options
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- options returned by `.opts()`
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The runtime is supplied by commander. This package is all about the typings.
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Usage
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- install `@commander-js/extra-typings` using your preferred package manager
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- install `commander`, if not already installed (peer dependency)
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- in code import from `@commander-js/extra-typings` instead of `commander`
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The installed version of this package should match the major and minor version numbers of the installed commander package, but the patch version number is independent (following pattern used by [Definitely Typed](https://github.com/DefinitelyTyped/DefinitelyTyped#how-do-definitely-typed-package-versions-relate-to-versions-of-the-corresponding-library)).
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Credit: this builds on work by @PaperStrike in <https://github.com/tj/commander.js/pull/1758>
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## Limitations
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- the generics lead to some noisy types visible in editor and errors
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- some minor code changes required for subclasses of `Command`, `Argument`, or `Option` (see [subclass.test-d.ts](./tests/subclass.test-d.ts))
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- chaining methods which do type inference return base class rather than `this`
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- subclass of `Command` returns base class not subclass from `.command(name)`
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- type parameter needed for class declaration of subclass of `Option` and `Argument`
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## Usage tips
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The types are built up as the options and arguments are defined. The usage pattern for action handlers is easy. Just chain the action handler after the options and arguments.
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```js
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import { program } from '@commander-js/extra-typings';
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program.command('print')
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.argument('<file>')
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.option('--double-sided')
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.action((targetFile, options) => {
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// command-arguments and options are fully typed
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});
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```
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For working with a single command without an action handler, the configuration need to be done at the same time as the variable is declared.
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```js
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import { Command } from '@commander-js/extra-typings';
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// broken pattern
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const program = new Command(); // program type does not include options or arguments
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program.option('-d, --debug'); // adding option does not change type of program
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const options = program.opts(); // dumb type
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```
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```js
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import { Command } from '@commander-js/extra-typings';
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// working pattern
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const program = new Command()
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.option('-d, --debug'); // program type includes chained options and arguments
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const options = program.opts(); // smart type
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```
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