https://github.com/hikari-no-yume/newtype

A handy function for creating opaque types
https://github.com/hikari-no-yume/newtype

Last synced: 9 days ago
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A handy function for creating opaque types

• Host: GitHub
• URL: https://github.com/hikari-no-yume/newtype
• Owner: hikari-no-yume
• License: other
• Created: 2015-11-10T21:54:04.000Z (about 9 years ago)
• Default Branch: master
• Last Pushed: 2018-01-24T19:56:46.000Z (almost 7 years ago)
• Last Synced: 2024-11-07T05:25:55.476Z (about 2 months ago)
• Language: PHP
• Homepage: https://packagist.org/packages/ajf/newtype
• Size: 26.4 KB
• Stars: 18
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# newType - Create an opaque type with a single line of code

`newType()` is a handy function for creating opaque types, that is, a type that merely wraps another type. It takes two parameters: the name of your new wrapper type, and the name of the type you want to wrap. You get a class with a constructor taking a value of the wrapped type, and an `->unbox()` method to get out the value of the wrapped type.

Require it with `composer require ajf/newtype` to use it. It's PHP 7-only, since PHP 7 is the first version of PHP with scalar type declarations. It would be possible to backport this, though.

An example of where you might use this:

```PHP

unbox(), $destinationPath->unbox());

}

moveFile(new FilePath('foo'), new FilePath('bar'));

```

Use it for that extra bit of type safety!

If you're after a mere alias that doesn't require explicit conversion to and from, check out [PHP's built-in `class\_alias` function](http://php.net/class_alias) - though beware that only works with classes and not primitive types.

The name comes from [Haskell's `newtype` declaration](https://wiki.haskell.org/Newtype), which does the same thing:

```Haskell

newtype FilePath = FilePath String

```

It's similar to [Hack's `newtype` declaration](http://docs.hhvm.com/manual/en/hack.typealiasing.opaquetypealiasing.php) as well, although that works a little differently.