EVALUATE

EVALUATE action

[attrname := ] EVALUATE(expression) ;

[attrname := ] EVALUATE(module [, defname ] ) ;

attrnameOptional. The action name, which turns the action into a definition, therefore not executed until the attrname is used as an action.
expressionThe function to call in an action context.
moduleThe module to evaluate.
defnameOptional. The name of a specific definition within the module to evaluate. If omitted, all definitions in the module are evaluated.

The first form of the EVALUATE action names an expression (typically a function call) to execute in an action context. This is mainly useful for calling functions that have side-effects, where you don't care about the return value.

The second form of the EVALUATE action recursively expands the exported definitions of the module and evaluates them. If a defname is specified, then only that definition is evaluated.

Example:

Form 1 example:

myService := SERVICE
  UNSIGNED4 doSomething(STRING text);
END;

ds := DATASET('MyFile', {STRING20 text} , THOR);

APPLY(ds, EVALUATE(doSomething(ds.text)));
 //calls the doSomething function once for each record in the ds
 // dataset, ignoring the returned values from the function

Form 2 example:

M := MODULE
  EXPORT a := 10;
  EXPORT b := OUTPUT('Hello');
END;
 
M2 := MODULE
  EXPORT mx := M;
  EXPORT d := OUTPUT('Richard');
END;
 
EVALUATE(M2); 
//produces three results:
//  Result_1: 10
//  Result_2: Hello
//  Result_3: Richard

See Also: APPLY, SERVICE Structure,