EiffelStudio’s differentiator: Design by Contract

EiffelStudio is based on Design by Contract, a method in which software behavior is defined through:

• Preconditions — what a component requires
• Postconditions — what it guarantees
• Invariants — what must always remain true

These contracts are:

• Part of the programming language
• Checked automatically
• Understood by the development tools

As a result, violations are detected at the point of failure, not after the fact.

What this changes in practice

For evaluators comparing tools, this approach delivers concrete advantages:

• Early fault detection
  Incorrect interactions are exposed immediately, reducing debugging time.
• Lower maintenance risk
  Contracts act as executable documentation that remains accurate as code evolves.
• Controlled system evolution
  Changes that violate system assumptions are detected automatically.
• Reduced reliance on defensive code
  Behavior is enforced by design, not scattered checks.

This is particularly valuable for long-lived, complex, or high-risk systems.

When EiffelStudio is the right choice

EiffelStudio is suited for:

• Solo programmers and Teams that value correctness over quick experimentation
• Mission-critical and safety-relevant systems
• Financial and infrastructure software
• Complex domains with evolving requirements

Why conventional tools fall short

Most development environments optimize for speed of coding and rely on testing to catch errors later.

This creates structural problems:

• Critical assumptions remain implicit
• Contracts between components are undocumented or informal
• Errors surface late, often in production
• Maintenance cost grows as systems evolve

Testing validates samples of behavior.
It does not define what must never happen.