A named expression is simply an expression or part of an expression that can be given a name in order to save typing and to reduce typing errors.
The syntax to surround a named expression is $ExpressionName$.
Example
|
Expression |
Saved as |
Insertion Syntax |
|
Order Card |
OC |
$OC$ |
Note: The $name$ syntax works just like an #include directive
in the “C” programming language. The $name$ is removed; the text it represents is
inserted; the expression evaluation continues.
A partial identifier or a partial literal will not work as a named expression.
Example
Assume
Order Card is an attribute group.
The following expression is invalid:
Given
|
O = |
Order |
|
C = |
Card |
This will not work because the group name is split in half.
$O$ $C$.A=’xyz’ fails.
A single token in the bnf syntax in the detail design is the smallest an expression can be.
Fractional tokens as demonstrated in this example are not supported.
No substitution occurs between quotes.
The following expression is invalid:
Given:
|
val= |
xyz |
Order Card.A=’$val$’ fails.
The following expression is valid.
Given:
“val=’xyz’”
“Order Card.A=$val$“ succeeds.
Expressions are context sensitive.
|
|
4. Named Query expressions. |
