(or/c #f ) vs
A binary search tree with a single value is constructed as: (bst 42 #f #f) Here #f is used to indicated that the left and right subtrees are empty. Since we want the left and right subtrees also to be binary search trees, we need to include the value #f...
Java: Design by Contract annotations
JavaDoc is inaccessible at runtime. The .class file doesn't contain them. (Reference see here StackOverflow question) Therefor, any code that would check for a javadoc is impossible. The comment is simply to make beautiful javadoc, or to keep the same pattern for these kind of notes across the classes. You'd...
Is a return of 'false' a valid postcondition of a method?
You did not provide any preconditions nor postconditions in your example method. What you provided was a class invariant. The precondition is checked in the method before the postcondition is checked. Often times this is done via assert for post-conditions. A postcondition states what a method ensures if it has...
WCF Contract first: No methods are exposed
xml,wcf,soap,wsdl,design-by-contract
Apparently svcutil adds ReplyAction="*" to the operation contract, and that causes the weird behaviour. After removing this specification of the OperationContractAttribute, the problem went away. [System.ServiceModel.ServiceContractAttribute(Namespace="http://tempuri.org/xml/wsdl/soap11/DistributionService/1/port", ConfigurationName="DistributionReceiverWebServicePort")] public interface DistributionReceiverWebServicePort { [System.ServiceModel.OperationContractAttribute(Action="")]...
How to use the method compile in smalltalk and what parameters can I call it with
smalltalk,squeak,design-by-contract
Since you mentioned this is a homework assignment, I will not deprive you of discovering the joys of a live, dynamic system like Smalltalk ;) The best tutor is your image itself. For many messages (including the one in question), there are helpful examples right under your finger tips that...
Hibernate Validator annotations not working
java,hibernate,bean-validation,design-by-contract
You should run the validation engine to check if it is valid or not: public class Driver { public static void main(String[] args) { Person p = new Person(); p.setName(null); ValidatorFactory factory = Validation.buildDefaultValidatorFactory(); Set<ConstraintViolation<Person>> constraints = factory.getValidator().validate(p); // constraint will have the results of validation } } You also...
Clojure condition-map parameter provided as metadata of the arglist
clojure,assertions,assertion,design-by-contract
(defn foo ^{:pre [(even? x)] :post [(pos? %)]} [x] ;; <-- metadata attached to arglist --> \ / ;; | ;; arglist -----/ (inc x)) Calling the above the REPL: user=> (foo 0) 1 user=> (foo -2) AssertionError Assert failed: (pos? %) user/foo (NO_SOURCE_FILE:2) user=> (foo 1) AssertionError Assert failed:...