Learn EIFFEL with Real Code Examples

Eiffel enforces object-oriented principles such as classes, inheritance, polymorphism, and genericity.

Design by Contract allows developers to specify preconditions, postconditions, and invariants for software correctness.

Used for building complex systems, safety-critical applications, and reusable libraries.

Classes, objects, and inheritance

Preconditions, postconditions, invariants

Genericity for reusable components

Deferred (abstract) and effective (concrete) classes

Exception handling and assertions

Classes, objects, and references

Features (methods) and attributes

Preconditions, postconditions, invariants

Generic classes

Inheritance and polymorphism

Class files (.e)

Library or module folders

Project configuration files

Generated binaries or executable

Documentation and contract specifications

Design class hierarchy and contracts

Implement classes and features

Compile with Eiffel compiler

Run and test with assertions enabled

Refactor and extend with reusable components

Beginner: simple classes and objects

Intermediate: inheritance and genericity

Advanced: large-scale systems with contracts

Expert: safety-critical and mission-critical applications

Higher emphasis on correctness than Java or C++

Integrated contract system vs external testing

Object-oriented like C++ or Java, but with design-by-contract

Less widespread than mainstream languages

Focus on software engineering rigor

1985 – Initial Eiffel design by Bertrand Meyer

1987 – First Eiffel compiler released

1990s – EiffelStudio development and evolution

2000s – Improved OO support and libraries

2010s–2025 – Modern EiffelStudio with updated libraries and tools

Feature: method or attribute of a class

Class: blueprint for objects

Precondition: condition before method execution

Postcondition: condition after method execution

Invariant: condition always true for class