This Validate function method returns a Boolean value that indicates whether the VALUE passed to it is valid for the parameter. If the VALUE is invalid, then 0 is returned and the ERROR keyword will be populated with information on why it is invalid. This method allows the user to test the VALUE before setting the parameter’s VALUE and generating an error that must be handled by the user routine.


Result = ENVIParameterENVIAgCrops.Validate(Value [, ERROR=variable])

Return Value

The result is a Boolean value indicating if the VALUE is valid for the parameter.



The current value of the parameter. The parameter's VALUE can be set at any time through ENVITask using "." dot notation using the NAME of the parameter, or directly on the parameter object. The value of this property must adhere to the TYPE property. Setting this property will internally invoke the Validate() method, and will throw an error if the new value is invalid. If you set VALUE to a one-element array, it will be converted to a scalar during validation.


ERROR (optional)

Set this keyword to a named variable that will contain any error message issued during execution of this routine. If no error occurs, the ERROR variable will be set to a null string (''). If an error occurs and the routine is a function, then the function result will be undefined.

When this keyword is not set and an error occurs, ENVI returns to the caller and execution halts. In this case, the error message is contained within !ERROR_STATE and can be caught using IDL's CATCH routine. See IDL Help for more information on !ERROR_STATE and CATCH.

See Manage Errors for more information on error handling in ENVI programming.

Version History

Crop Science 1.1


API Version


See Also