Cross Ref > Language Details

ObjectPAL is a non-OOP language (an object-based language) that offers custom methods and custom procedures. When you create a custom method, you associate it with an existing object like a button, form, or library.

When calling a custom method or procedure that has a by reference parameter (uses var), then you cannot use a literal value. this is different than in many other languages which do allow you to pass literals by reference.

method sayHello(var pName String)
 msgInfo("", "Hello " + pName)
endMethod
 

method add(p1 Number, p2 Number) Number
 Return p1 + p2
endMethod

 ObjectPAL Custom Routines (method, procedure)  

Access VBA is a non-OOP language with some OOP features. It offers both Subs and Functions. A Sub does not return a value while a Function does. When Subs and Functions are used in a class module, they become the methods of the class.

Sub SayHello(ByVal pName As String)

  MsgBox ("Hello " & pName)

End Sub

Function Add(pN1 As Integer, pN2 As Integer) As Integer

  Add = pN1 + pN2

End Function

 Access VBA Custom Routines (Sub, Function)

Paradox & Overloading

• Operator - No.
• Method - No.

However, you can have the same named method or procedure so long as they are in different libraries. This is important if you use libraries in a class-like OOP way and wish to implement some form of polymorphism (i.e. libMember.Open and libVendor.Open). This is an OOP-like technique for implementing a subtyping-like polymorphism which is also known as inclusion polymorphism.

Also, some developers like to pass an array and then handle the array for a pseudo technique. Although not overloading, it's useful.

 ObjectPAL Overloading  

Some developers like to pass in an array and then handle the array for a pseudo technique but that's not really overloading.

By Reference or Value (and by constant)
The default for parameters is by value. For by reference, add var in front of the parameter. ObjectPAL also offers constant parameters where you add const in front of the parameter. A constant parameter is like a read-only parameter the compiler can optimize. You cannot assign a value to a constant parameter.

Syntax Example:   method cmCode(s String) ;...s is by value. endMethod   method pushButton(var eventInfo Event)   ;...eventInfo is by reference. endMethod   method cmCode(Const s String)   ;...s is a constant read-only parameter. endMethod    proc cpNever() String   return "Never duplicate a line of code!" endProc

By Reference or Value
For parameters, you can optionally specify ByVal or ByRef. ByRef is the default if you don't specify.

Syntax Example:   Function SomeRoutine(ByRef pPerson, ByVal pName, Age)

A built-in object variable that represents the UIObject to which the currently executing code is attached.

Syntax Example:   method pushButton(var eventInfo Event)   msgInfo("", self.Name) endMethod

Same as VB. The Me keyword is a built-in variable that refers to the class where the code is executing. For example, you can pass Me from one module to another.

Private Sub Command10_Click()
    MsgBox Me.Name  'Displays name of form (Form1 in this case).

End Sub