GolfService Example

The GolfService Example Class illustrates the use of nested classes. GolfService was originally developed as a Web Service for Dyalog.NET and is one of the samples distributed in samples\asp.net\webservices. This version has been reconstructed as a stand-alone APL Class.

GolfService contains the following nested classes, all of which are Private.

GolfCourse A Class that represents a Golf Course, having Fields Code and Name .
Slot A Class that represents a tee-time or match, having Fields Time and Players . Up to 4 players may play together in a match.
Booking A Class that represents a reservation for a particular tee-time at a particular golf course. This has Fields OK , Course , TeeTime and Message . The value of TeeTime is an Instance of a Slot Class.
StartingSheet A Class that represents a day's starting-sheet at a particular golf course. It has Fields OK , Course , Date , Slots , Message . Slots is an array of Instances of Slot Class.

The GolfService constructor takes the name of a file in which all the data is stored. This file is initialised by method InitFile if it doesn't already exist. 

      G←⎕NEW GolfService 'F:\HELP11.0\GOLFDATA'
      G
#.[Instance of GolfService]

The GetCourses method returns an array of Instances of the internal (nested) Class GolfCourse. Notice how the display form of each Instance is established by the GolfCourse constructor, to obtain the output display shown below. 

      G.GetCourses
 St Andrews(1)  Hindhead(2)  Basingstoke(3)

All of the dates and times employ instances of the .NET type System.DateTime, and the following statements just set up some temporary variables for convenience later. 

      ⎕←Tomorrow←(⎕NEW DateTime(3↑⎕TS)).AddDays 1
31/03/2006 00:00:00
      ⎕←TomorrowAt7←Tomorrow.AddHours 7
31/03/2006 07:00:00

The MakeBooking method takes between 4 and 7 parameters viz.

  • the code for the golf course at which the reservation is required
  • the date and time of the reservation
  • a flag to indicate whether or not the nearest available time will do

  • a list of up to 4 players who wish to book that time.

  • the code for the golf course at which the reservation is required

  • the date and time of the reservation
  • a flag to indicate whether or not the nearest available time will do
  • a list of up to 4 players who wish to book that time.

The result is an Instance of the internal Class Booking. Once again, ⎕DF is used to make the default display of these Instances meaningful. In this case, the reservation is successful. 

      G.MakeBooking 2 TomorrowAt7 1 'Pete' 'Tiger'
  Hindhead(2)   31/03/2006 07:00:00   Pete  Tiger    OK

Bob, Arnie and Jack also ask to play at 7:00 but are given the 7:10 tee-time instead (4-player restriction). 

      G.MakeBooking 2 TomorrowAt7 1 'Bob' 'Arnie' 'Jack'
 Hindhead(2)   31/03/2006 07:10:00   Bob  Arnie  Jack    OK

However, Pete and Tiger are joined at 7:00 by Dave and Al. 

       G.MakeBooking 2 TomorrowAt7 1 'Dave' 'Al'
  Hindhead(2)   31/03/2006 07:00:00   Pete  Tiger  Dave  Al    OK

Up to now, all bookings have been made with the tee-time flexibility flag set to 1. Inflexible Jim is only interested in playing at 7:00... 

      G.MakeBooking 2 TomorrowAt7 0 'Jim'
 Hindhead(2)  31/03/2006 07:00:00  Not available

... so his reservation fails (4-player restriction).

Finally the GetStartingSheet method is used to obtain an Instance of the internal Class StartingSheet for the given course and day. 

      G.GetStartingSheet 2 Tomorrow
  Hindhead(2)  31/03/2006 00:00:00              
  31/03/2006 07:00:00   Pete  Tiger  Dave  Al   
  31/03/2006 07:10:00   Bob  Arnie  Jack        
  31/03/2006 07:20:00                           
  ....