Rel version 1.0.4 Beta now available

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Dave
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Posts: 367
Joined: Sun Nov 27, 2005 7:19 pm

Rel version 1.0.4 Beta now available

Post by Dave » Sun Sep 12, 2010 8:53 pm

This version of Rel provides two enhancements and several bug fixes.

Enhancements:

1. Inference of most specific common supertype (excluding Alpha) has been implemented, such that evaluating...

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  RELATION {
    TUPLE {x Triangle(Point(0,0), Point(2,3), Point(7,4))}
    TUPLE {x Square(Point(1,1), Point(4,3))}
  }
...returns...

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  RELATION {x Shape} {
    TUPLE {x Triangle(Point(0,0), Point(2,3), Point(7,4))}
    TUPLE {x Square(Point(1,1), Point(4,3))}
  }
...assuming the existence of types 'Triangle' and 'Square' which are subtypes of 'Shape'.

2. Selectors are now generated for immediate subtypes of built-in types, as per Date & Darwen's "Database Explorations" (ISBN 978-1-4269-3723-1), Chapter 21, page 348 "Selectors for System Defined Types". E.g., the following...

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  TYPE PosInt IS {INTEGER CONSTRAINT INTEGER >= 0};
...will automatically create a selector called PosInt which accepts an INTEGER as its sole argument and returns a PosInt value.

Bug Fixes:

1. A derived POSSREP definition list should be allowed to be empty when defining a type whose immediate supertype is a built-in type. However, Rel previously required at least one POSSREP. E.g., the following legitimate definition was not allowed:

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  TYPE PosInt IS {INTEGER CONSTRAINT INTEGER >= 0};
This has been fixed.

2. A bug has been corrected that could, in rare circumstances, cause a database to fail to open due to an internal "LOG INTEGRITY" error.

3. A bug has been corrected that could, in rare circumstances, cause corruption of user-defined type values when inserted into a relvar immediately after any Rel error (e.g., a syntax error) has been generated.

For more information, or to download Rel, see http://dbappbuilder.sourceforge.net/Rel.html

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