Specification.dart

Implementation of the Specification pattern in Domain Driven Design by Dart.

What is the specificaiton pattern?

the specification pattern is a particular software design pattern, whereby business rules can be recombined by chaining the business rules together using boolean logic.

"Specification pattern." Wikipedia: The Free Encyclopedia. Wikimedia Foundation, Inc. 15 April 2013. Web. 27 April 2013.

Examples

import 'package:specification/specification.dart' as spec;

main () {
  var spec1 = spec.expr((value) => value.length > 2);
  var spec2 = spec.expr((String str) => str.startsWith("abc"));
  
  var conjunction = spec1 & spec2;
  print(conjunction.isSatisfiedBy("a"));      // false
  print(conjunction.isSatisfiedBy("abb"));    // false
  print(conjunction.isSatisfiedBy("abcde"));  // true
  
  var disjuction = spec1 | spec2;
  print(disjuction.isSatisfiedBy("a"));       // false
  print(disjuction.isSatisfiedBy("abb"));     // true
  print(disjuction.isSatisfiedBy("abcde"));   // true
  
  var negation = ~spec1;
  print(negation.isSatisfiedBy("a"));         // true
  print(negation.isSatisfiedBy("abb"));       // false
  print(negation.isSatisfiedBy("abcde""));     // false
  
  var exclusiveDisjunction = spec1 ^ spec2;
  print(exclusiveDisjunction.isSatisfiedBy("a"));     // false
  print(exclusiveDisjunction.isSatisfiedBy("abb"));   // true
  print(exclusiveDisjunction.isSatisfiedBy("abcde")); // false
}

Licence

see LICENSE

Author

• Tomochika Hara(@zetta1985)