optional 5.0.0+1

An implementation of the Optional type, which helps avoid dealing with null references

Changelog

5.0.0

• Refactored async support to orElseGetAsync() to avoid bogus dartanalyzer errors
• (Breaking change) or*() methods no longer support async. Instead, use orElseGetAsync()

4.2.0

• Added async support
  • The or*() methods now accept and return FutureOr

4.1.0

• Optional now implements Iterable
  • The toSet() and toList() methods now return modifiable collections.
  • The toList() method now accepts a growable optional named parameter, to comply with the Iterable interface.

4.0.1

• Fixed dartdoc generation

4.0.0

• Added toOptional extension method
• Note that this requires the minimum SDK version to be 2.6.0, please continue to use version 3.1.0 if upgrading to SDK version 2.6.0 is not an option.

3.1.0

• Added contains(val) method.
• Added toSet() method.
• Added toList() method.

3.0.2

• Fix Present cast() issue

3.0.1

• Absent cast() method bug-fix

3.0.0

• (Breaking change) Removed operator overloads. They were breaking strong-mode type checks.
• (Breaking change) Made equality checks more consistent with Dart standards. Now any two empty Optionals are equal, and two non-empty Optionals are equal if their values are equal, regardless of their types.
• Added a cast() method, similar to List.cast().

2.0.2

• Better use of generic methods (no more dynamic).

2.0.0

• Compatibility with Dart 2

1.2.3

• Add an optional orElse parameter to ifPresent.

1.2.2

• Optional.empty() constructor is now const.

1.2.1

• Absent and Present are now subclasses of Optional. You should continue to use constructors in Optional, and not the Absent or Present ones.
• EMPTY is now a top-level constant.

1.2.0

• Operators are now overloaded, so you can add, subtract, etc., Optionals. Any operation involving an empty Optional will return an empty Optional.
• Added examples.

1.1.0

• Optional.ofNullable() and Optional.empty() constructors are now const.
• Optional.of() constructor now throws ArgumentError when passed null, instead of NoValuePresentError.
• NoValuePresentError now extends StateError.

1.0.0

• Initial release