4.1. Guidelines for Simple Named Expressions
Procedure
-
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.