• Simple Mode Video
• Access the IDE in a browwser (EECS or Passport York Login required)

Below is a Demo of a Capstone Project by two students: Webapp for compiling/executing Eiffel programs with a selection of coding challenges illustrating Design by Contract.

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The above video demos the simple mode, but there is also a project and tutorial mode. It is more challenging to develop a robust web-app of this kind than a desktop application.

See More details of the student capstone features and design.

In Design by Contract (developed by Bertrand Meyer), a software component has a mathematical specification that describes what the the component must do (free of implementation detail) and an implementation (one of possibly many) that describes how the specification is implemented.

For example, the specification of a a square root function is described by a precondition (keyword require) and a postcondition (keyword ensure) as shown below.

There are of course many different implementations that might satisfy this specification.

A contract imposes obligations and benefits on the client (a component that uses the square root function) and the supplier (who must provide a body for the square root function).

A precondition failure is the fault of the client of the component. A postcondition failure is the fault of the supplier of the failure.

Runtime assertion checking (in Eiffel) is used to check that the given implementation satisfies the specification.