Eiffel Breaking Changes

Revision as of 04:43, 21 January 2016 by Manus (Talk | contribs) (Strings)

Warning.png Warning: Article under development


As of this writing, January 21st 2016, the Eiffel language has slowly evolved over the years and added numerous new facilities. Initially, the changes were done by Eiffel Software while maintaining backward compatibility. Then, a major work was done between 2001 and 2005 to standardize the language which became an ECMA standard in 2005 (ECMA-367) and an ISO standard in 2006 (ISO/IEC 25436:2006). That work established some constructs initially implemented in EiffelStudio and also introduced some new ones. Most of the changes introduced by the standardization have been implemented but there are quite a few remaining. In some cases, it is due to the ration cost/benefit of the implementation, in some others it is a breaking changes.

This page is going to list all the changes that needs to be done by Eiffel Software to conform to the standard which cover both the language but also the library facilities required to support the language specification.

Library changes





STRING should be the equivalent of what IMMUTABLE_STRING_32 was before. STRING_8 should be the equivalent of what IMMUTABLE_STRING_8 was before. MUTABLE_STRING_8 should be the equivalent of what STRING_8 was before. MUTABLE_STRING_32 should be the equivalent of what STRING_32 was before.


When STRING_32 was added, we did not want to break existing code if it became the default. For example, many Eiffel libraries having a binding with C, could directly use an Eiffel STRING object as argument to a C routines. Of course this is very dangerous and we have changed this over the year to introduce safer mechanism (such as C_STRING).

Now the world is Unicode, not using a Unicode string by default does not make sense. On top of that, string instances are rarely modified and we have seen over the year many bugs because users have a tendency to forget this important fact. Which caused a lot of code to duplicate strings just to be sure, making the code less efficient. This is why we want to map STRING to IMMUTABLE_STRING_32.

The end benefit is that we would have cleaner string manipulations and more importantly much more efficient string operations (search, string sharing, traversals, ...)


A lot of code would not compile anymore by this change. Pretty much all libraries would have to be rewritten.