The trailing arguments in the argument list of an operation may be optional. If these trailing arguments are missing in a call of an operation the default argument values given in the specification are used. Passing by reference must always be used if the operation is to change the value of the argument. It should always be used for passing large objects such as lists, arrays, graphs and other LEDA data types to functions. Otherwise a complete copy of the actual argument is made, which takes time proportional to its size, whereas passing by reference always takes constant time.
Some operations take functions as arguments.
For instance the bucket sort operation on lists requires a function which maps the elements of the list into an interval of integers. Copyright 1998-2001, Algorithmic Solutions Software GmbH . All rights reserved.