MultiResult

Multiresult lets a User-Defined Function or expression return more than one distinct value. It is also convenient in some loops when you want to set multiple local variables at the same time.

_( expr ... )

These two equivalent functions accept repeated expressions separated by commas. It evaluates the only the ones that are captured by the caller or parent expression, and returns the results as multiple distinct return values. The dimensions of each return value are kept distinct -- they are not combined in any way as they would in other functions. MultiResult(a,b,c) and _(a,b,c) are identical in functionality. Stylistically, the MultiResult(...) syntax is generally nicer when used for a UDF return value, and the _(...) notation lends itself to looping constructs.

Examples

This function returns the R, G, B and Alpha components as separate results given a color integer c.

Function ColorComponents(c: Color ) :=

MultiResult(

BitAnd( [ BitShift( c, 16), 0xFF] ),

BitAnd( [ BitShift( c, 8), 0xFF] ),

BitAnd( [ c, 0xFF] ),

BitAnd( [ BitShift( c, 24), 0xFF] ) )

You can then capture the separate return values in local values using, e.g.,

Local (r,g,b,a) := ColorComponents( 'Turquoise' );

When you don't need the alpha value,

Local (r,g,b) := ColorComponents( 'Turquoise' );

In this case, the final expression BitAnd( [ BitShift( c, 24), 0xFF] ) in the UDF does not get evaluated.

The next example illustrates its use in a looping construct. Here v is indexed by Time and In1, but the «bodyExpr» does something where it requires v to be indexed only by Time. At the same time, it also needs to know the corresponding index value from In1 for that slice of v.

Local ( vi[Time], i[ ] ) := _( v, In1);

«bodyExpr»

History

Added in release 5.2.

See Also

• Local
• User-Defined Functions