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Methods

Calling Methods

A method is similar to a function in that it may or may not take an argument, perform some action, and return a result.

Examples are the Print, NewPage, Setup and Abort methods, all of which cause a Printer object to take a particular action.

If the system variable ⎕WX is 1, you may invoke an object's method using exactly the same syntax as you would use to call a function in that object.

For example, to execute the IDNToDate method of a Calendar object named F.CAL, you can use the expression: 

      F.CAL.IDNToDate 36525
2000 1 1 5

When you call a method in this way, the method name is case-sensitive and if you spell it incorrectly, you will get a VALUE ERROR. 

      F.CAL.idntodate 36525
VALUE ERROR
      F.C.idntodate 36525
     ^

Invoking Methods with ⎕NQ

Methods may also be called using ⎕NQ with a left argument of 2, indeed if ⎕WX is 0, this is the only way to call a method.

The result of the method is returned by ⎕NQ. Note however that the result is shy.

For example, for a TreeView object you can obtain status information about a particular item in the object using the GetItemState method: 

      ⎕←2 ⎕NQ 'f.tv' 'GetItemState' 6
96

Or you can call the IDNToDate method of a Calendar object F.C as follows: 

     ⎕←2 ⎕NQ 'F.CAL' 'IDNToDate' 36525
2000 1 1 5

When you call a method using 2 ⎕NQ, the method name is not case-sensitive. 

     ⎕←2 ⎕NQ 'F.CAL' 'idntodate' 36525
2000 1 1 5

Events as Methods

Methods and events are closely related and most events can be invoked as methods.

For example, you can reposition and resize a Form in one step by calling its Configure event as a method. The argument you supply is the same as the event message associated with the event, but with the first two items (Object and Event code) omitted. 

      F.Configure 10 10 30 20

Or, using 2 ⎕NQ 

     2 ⎕NQ 'F' 'Configure' 10 10 30 20

Notice that when you call an event as a method, you are executing the default processing associated with the event. The setting for the Event property is ignored and, in particular, any callback associated with the event is not executed.