PropertyHandle :: ExpandFilter - Expand filter condition
The function expands the filter condition currently set in the property handle by the expression passed to the function. The current filter is combined with the expression passed by an AND operation (reduction). In order to expand the collection of selected instances one may pass the or_opt (true or YES).
The function returns the current filter condition. Thus, cascading selection can be set and reset by restoring the returned filter condition later on.
When no or an empty expression is passed to the function, the filter condition does not change, but will be returned from the function.
When no filter condition was set when calling the function, it returns an empty string. When an error has encountered, the function returns NULL.
Implementation details
- expression
- Inline expression
An ad hoc expression can be passed as operand (something like a + b) or as complete expression. As operand, an expression may contain any expression, which is allowed in a statement, but no semicolon should be appended. Complete expressions include expression header (optional) and may include different sections in the expression body which is enclosed in { ... }.
In contrast to class expressions, ad hoc expressions are not defined explicitly as class expressions but passed as strings to the application at run time.
operand: a + funct(b)
complete expression :
bool expr(int a)
{
return(a*a);
}
- or_opt
- OR option
The or option indicates that an OR operation has been requested rather than an AND operation.
Default: NO