Tower Eiffel

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The first commercial implementation of Eiffel and what appears to be the first working Eiffel 3 implementation, period. Produced by Atlanta, Georgia, USA based company Tower Technology for Sun SPARC workstations in 1993, an OS/2 version shipped in early 1994, most popular Unix and Unix like workstation OS's getting a version later in 1994 or 1995, and a Windows NT port showing up in 1996. The Tower Eiffel became quite well known in the industry and something of a de-facto standard for a while not the least since it had strong C++ interoperability features, not only allowing C++ objects to be invoked from Eiffel and vice versa but the compiler could optionally emit C++ code instead of native machine code.

The company also announced a version with native thread support, SOM code generation and OpenDOC support for both OS/2 and AIX in 1996, although a version of this toolkit was allegedly in Beta, the OS/2 version was dropped suddenly in 1997 and in the end only Windows NT, AIX and Solaris got native thread support, but the AIX version lacked the promised SOM support.

The drop of the OS/2 version of the compiler caused some stir in the Eiffel community and this led to the instigation of an OS/2 port of ISE Eiffel by language designer Bertrand Meyer himself in 1998, this was unusual since by that time IBM had already dropped the system, but apparently there were some large accounts with considerable investment in OS/2 systems built with the Tower Eiffel system.

Classes and bindings

  • Tower Eiffel Booch Classes - Freeware release of the old Booch classes that were developed by Rational but Tower used to sell, work with v2 of Tower Eiffel.
  • The system could be bought with the O2 Technology O2 System object oriented database, or if you already had Tower Eiffel, Tower would sell you the O2 System as an add-on.
Other Tower Eiffel tools
  • The company offered a RAD GUI design tools for X Window System/Motif in 1996 called X-Designer that was licensed from V.I. Corporation, it retailed for USD 3495, and could be made to work on OS/2 if you had an X client/server set-up or emulator, but of limited use.


  • Last known version for Unix Workstations and Windows: 2.0x - 1998
  • Last known OS/2 version: v2 - 1996 (Possibly bugfix v2.x or v2.0x in 1997)
  • Version 1.2 - January 1994 - Allows interoperation with C and C++ tools, either way. - First OS/2 release
  • Version 1 - September 1993 - Initial release



  • Commercial - Discontinued
  • A single commercial for TowerEiffel was sold for USD 1295, an "individual license" that forbade non-commercial use a was sold for 390 USD, full-time students or students taking an approved Eiffel class got it for USD 259, and University professors got it for USD 129. (Note, USA Professor = EU/RoW Lector or even Adjunct)