From SmartEiffelWiki

This page is about language compatibility for SmartEiffel. You can find here the most important differences between SmartEiffel and other similar languages. The list is not intended to be exhaustive, it just intends to highlight the most important differences.

Unique peculiarities of SmartEiffel

SmartEiffel has some features not implemented by any other implementation:

  • Case sensitivity: "abc", "Abc" and "ABC" are different identifiers
  • Compiler-enforced casing rules: Class names must be all-uppercase; camelCase is not allowed.
  • ANY is the root of the inheritance tree, but not of the conformance tree.
  • Conformance rules related to expanded types.
  • Non-conforming inheritance. See Conforming and non-conforming inheritance
  • The notation for non-conforming inheritance is "insert <Type_Class>".
  • New operators for run-time type checking. See Dynamic type testing
  • Removed the danger of automatic boxing (object allocation on assignment of expanded types to reference entities)
  • Lots of additional tools in the library. See The SmartEiffel general purpose library
  • Notation for manifest collections. The old <<...>> is still supported for simple arrays.
  • Unicode strings manifest notation.
  • Agents look contravarient. But they are not. Believe us. For details and explanations, see this article (

Differences between ETL2 and SmartEiffel

SmartEiffel was at some time based on ETL2; as all the members of the Eiffel language family, it has grown and improved on that, adding several features (some of them also implemented by other compilers)

  • The "Precursor" mechanism (proposed at OOSC2). see Precursor
  • Agents and tuples. see Agent and Tuple

Differences between SmartEiffel and ECMA Eiffel

The ECMA Eiffel specification ( does not describe any current implementation at the time of writing this (November 2005). Despite being a standard it describes several features that fork away from what has been always called "Eiffel". The following aspects of ECMA Eiffel will not be implemented in SmartEiffel:

  • Conversions (implemented in ISE Eiffel)
  • Feature aliases (implemented in ISE Eiffel)
  • Bracket indexing (implemented in ISE Eiffel)
  • No-variant agent arguments.

On the other hand, the following features were taken from the ECMA specification process:

  • Non-conforming inheritance (although the notation is different)
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