# Section 8.1.2.3:
ELT_LT

###### class ELT_LT{ETP}

#### Formal Types

types
SAME = ELT_LT_ETP ;

This class provides the equality comparison function for elements of type ETP. If no other method has been provided then a default implementation-defined ordering relation is used.

It should be noted that it cannot be a partial class because of the rule that a call into a partial class cannot be made from within another partial class.

#### elt_lt

This is the sole predicate provided by this class. If the argument class derives from $IS_LT then the ordering relation provided in that class is used, otherwise if the arguments are immutable then an exception is raised, otherwise the implementation-defined ordering relation is used.

elt_lt | (
| first : ETP,
| second : ETP
| ) : BOOL

##### Formal Signature

elt_lt(first, second : ETP) res : BOOL

##### Pre-condition

Since this operation is a predicate the only pre-condition has to be true.

##### Post-condition

The formal post-condition is expressed as being equality in vdm terms. This is true if the argument type has a defined ordering relation, otherwise it must be informally recognised as implying an implementation-defined ordering relation.

post res = (first < second)

This predicate returns true if and only if the first argument precedes the second using the applicable ordering relation. The relation used is the class defined is_lt routine if the argument type is a subtype of $IS_LT, otherwise it uses the implementation-defined object ordering relation test is used.

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Comments or enquiries should be made to Keith Hopper . Page last modified: Wednesday, 24 May 2000. |