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From: marcap@doyle.cs.concordia.ca (PAWLOWSKY marc)
Newsgroups: comp.lang.eiffel
Subject: BASIC TYPES
Summary: The compiler should be able to handle basic types as normal objects
Message-ID: <1864@clyde.concordia.ca>
Date: 19 Feb 90 19:59:07 GMT
Sender: usenet@clyde.concordia.ca
Reply-To: marcap@doyle.CS.Concordia.CA (PAWLOWSKY marc)
Organization: Concordia University, Montreal Quebec
Lines: 52

ASSUMPTIONS:

  The definition for INTEGER is int.e
    (It inherits from comparable).

  The compiler handles basic types (INT, STRING, REAL, .. ) specially

THE EXAMPLE

  ARRAYS that can be sorted.

THE PROBLEM

  ec can not handle constraints on basic types.

DISCUSSION

  Creating a constrained generic type is very basic to OOP and Eiffel
  in particular.  However the basic types for 2.2 can not be passed
  as constrained parameters.

  This limitation is most annoying.  Since to bypass it artificial types
  become necessary, making the situation more complex than necessary.

  For example the class ARRAY_COMPAR

    class ARRAY_COMPAR[T -> COMPARABLE]

    export
      repeat ARRAY,
      is_sorted, quick_sort, merge
  
    inherit
      ARRAY[T] rename Create as array_create
  
  can not be used with a basic type.  Trying to do so results in the
  error message

    Eiffel compilation manager
       (version 2.2 level A)
    Pass 3 on class test_array_compar
    "test_array_compar", 15: Basic type may not be used as actual generic type corresponding to
    a constrained formal generic parameter
    es: error in pass3

  I do not think the compiler should treat basic types any different from
  other types when being passed.  If the resulting code is more inefficent
  than so be it.  Otherwise a class is necessary for each basic type, as
  well as another class for non-basic types.  I do not believe this is
  in the "spirit" of Eiffels concepts on reusability.

Marc Pawlowsky   Graduate Student     Concordia University