It won't be Eiffel

Bertrand Meyers has made the case, repeatedly, for design-by-contract as a way to improve the quality of computer programs. He has been doing so for the better part of two decades, and perhaps longer.

Design-by-contract is a notion that uses preconditions, postconditions, and invariants in object-oriented programs. Each is a form of an assertion, a test that is performed at a specific time. (Preconditions are performed prior to a function, postconditions after, etc.)

Design-by-contract is a way of ensuring that programs are correct. It adds rigor to programs, and  requires careful analysis and thought in the design of software. (Much like structured programming required analysis and thought for the design of software.)

I think it has a good chance of being accepted as a standard programming practice. It follows the improvements we have seen in programming languages: Bounds checking of indexes for arrays, function signatures, and type checking rules for casting from one type to another.

Someone will create a language that uses the design-by-contract concepts, and the language will gain popularity. Perhaps because of the vendor (Microsoft? Google?) or perhaps through grass-roots acceptance (a la Python).

There already is a language that implements design-by-contract: Eiffel, Meyers' pet language. It is available today, even for Linux, so developers can experiment with it. Yet it has little interest. The Eiffel language does not appear on the Tiobe index (at least not for September 2018) at all -- not only not in the top 20, but not in the top 100. (It may be lurking somewhere below that.)

So while I think that design-by-contract may succeed in the future, I also think that Eiffel has missed its opportunity. It hasn't been accepted by any of the big vendors (Microsoft, Oracle, Google, Apple) and its popularity remains low.

I think that another language may pick up the notion of preconditions and postconditions. The term "Design by contract" is trademarked by Meyers, so it is doubtful that another language will use it. But the term is not important -- it is the assertions that bring the rigor to programming. These are useful, and eventually will be found valuable by the development community.

At that point, multiple languages will support preconditions and postconditions. There will be new languages with the feature, and adaptations of existing languages (C++, Java, C#, and others) that sport preconditions and postconditions. So Bertrand Meyer will have "won" in the sense that his ideas were adopted.

But Eiffel, the language, will be left out.