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)  

Because java is an OOP language, all custom routines belong to a specific class and are therefore referred to as methods.

All methods in Java must return something so even with procedures, you return a "void".

public void sayHello(String pName) {
  System.out.println("Hello" + pName);
}

 

public int add(int p1, int p2) {

  return p1 + p2;

}

You cannot embed assembly in a java program but you can get system information via jni.

The Java compiler automatically inlines when it determines  a benefit. The use of final methods is considered a compiler hint to tell the compiler to inline the method if beneficial.

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  

Java Overloading

• Operator - No. Sun deliberately chose not include operator overloading in the Java language.
• Method - Yes.

 Java 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

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