CLASS variable scope fail

[patrickokeeffe]

I've created a class with local variables and a few functions but the functions are unable to access the variables. It wasn't clear I was doing it right so I copied the following from the OOP tutorial into a new sequence and tried to make it work:

class Person
   local string name = "name"		  // added = "name"
   local string address = "address"	// added = "address"
   local string zip = "zip"			// added = "zip"

   function OnCreate()	 // added this function
	  ? "onCreate"			// results in two "onCreate" printed
	  PrintMe()			   // doesn't print anything or cause errors
   endfunction

   function OnDestroy()	// added this function
	  ? "onDestroy"		   // results in two "onDestroy" printed
   endfunction

   function PrintMe()
	  ? name
	  ? address
	  ? zip
  endfunction
endclass

class PersonPhone parent Person
  local string phone

  function PrintMe()
	? name
	? address
	? zip
	? phone
  endfunction
endclass

People[0] = new(Person)
People[0].name = "Frank Smith"
People[0].address = "123 Main St"
People[0].zip = "12345"
//People[0].PrintMe()			  // causes C1000 error
//? People[0].name				 // causes C1000 error

People[1] = new(PersonPhone)
People[1].name = "George Johnson"
People[1].address = "123 Charles St"
People[1].zip = "54321"
People[1].phone = "555-1212"
//People[1].PrintMe()			  // causes C1000 error

? "Still alive?"				   // printed between onCreate's and onDestroy's

//? NumRows(People)				// causes C1000 error
//for (private.x = 0, x < numrows(People), x++)   // causes C1000 error
//People[x].PrintMe()
//endfor

My results were very different than expected. Using the original code results in C1000 errors; run as-is the sequence outputs:

onCreate
onCreate
Still alive?
onDestroy
onDestroy

Does anyone understand what's wrong here?

I'm using Base Release 5.84 Build 1636

[AzeoTech]

Its because you nevere declared the "people" variable. new() is still executing, but basically the result is being assigned to nothing because "people" doesn't exist. DAQFactory doesn't generate errors when you try and assign to something that doesn't exist. However, it does throw errors when you try and call a function that doesn't exist, and that's why you get the C1000 error when you call PrintMe(). Add "private people" before all the assignments and it will work.

Two other points:

1) OnCreate is limited in what you can do because its called before the object fully exists, thus the reason you don't see output when you try and call printMe. I actually prefer to create my own Init() function so I can control it.

2) Objects aren't necessarily destroyed when you think. DAQFactory's garbage collection runs async, so just because all references to an object go out of scope, doesn't mean the object is going to be destroyed right away. So, you may see a delay before OnDestroy is called.

[patrickokeeffe]

Ok, I modified the code to include a declaration and exclude the onCreate/onDestroy events but it still gives an error accessing a variable and, oddly, still printed my onCreate/Destroy messages.

class Person
   local string name 
   local string address 
   local string zip 

   function PrintMe()
	  ? "Name: "+name
	  ? "Addr: "+address
	  ? "Zip:  "+zip
  endfunction
endclass

class PersonPhone parent Person
  local string phone

  function PrintMe()
	? "Name: "+name
	? "Addr: "+address
	? "Zip:  "+zip
	? "Ph #: "+phone
  endfunction
endclass

private people

People[0] = new(Person)
People[0].name = "Person One"
People[0].address = "123 Main St"
People[0].zip = "12345"

People[1] = new(PersonPhone)
People[1].name = "Person Two"
People[1].address = "123 Charles St"
People[1].zip = "54321"
People[1].phone = "555-1212"

for (private.x = 0, x < numrows(People), x++)
   ? "Person "+doubletostr(x)
   People[x].PrintMe()
endfor

Here is the command window output after clearing the global space and running the script twice:

clearglobals()

onCreate

onCreate

Person 0

Name: Person One

Addr: 123 Main St

Zip: 12345

Person 1

Name: name

Addr: address

Zip: zip

12/07/10 11:50:46.557

C1086 One of the parameters was empty: Line 5: OOPtest Line 39 - Uncaught error in sequence OOPtest

onDestroy

onDestroy

onCreate

onCreate

Person 0

Name: Person One

Addr: 123 Main St

Zip: 12345

Person 1

Name: name

Addr: address

Zip: zip

12/07/10 11:51:14.739

C1086 One of the parameters was empty: Line 5: OOPtest Line 39 - Uncaught error in sequence OOPtest

onDestroy

onDestroy

Completely restarting DAQFactory finally stopped the onCreate/onDestroy messages and also caused the three lines after "Person 1" containing values of "name", "address", and "zip" to stop appearing (which makes me wonder about garbage collection); it did not solve the C1086 error, however. Thinking it could be related to objects inside arrays, I made the code simpler:

class Person
   local string name 
   local string address 
   local string zip 

   function PrintMe()
	  ? "Name: "+name
	  ? "Addr: "+address
	  ? "Zip1: "+zip
  endfunction
endclass

class PersonPhone parent Person
  local string phone

  function PrintMe()
	? "Name: "+name
	? "Addr: "+address
	? "Zip2: "+zip
	? "Ph #: "+phone
  endfunction
endclass

private people
private peeple

People = new(Person)
People.name = "Person One"
People.address = "123 Main St"
People.zip = "12345"

Peeple = new(PersonPhone)
Peeple.name = "Person Two"
Peeple.address = "123 Charles St"
Peeple.zip = "54321"
Peeple.phone = "555-1212"

? "Person 1"
People.PrintMe()
? "Person 2"
Peeple.PrintMe()

And it still fails:

Person 1

Name: Person One

Addr: 123 Main St

Zip1: 12345

Person 2

12/07/10 12:22:13.126

C1086 One of the parameters was empty: Line 2: OOPtest Line 59 - Uncaught error in sequence OOPtest

I'm not sure why this child class doesn't seem to inherit from its parent but I'm developing a class with children and am having parallel problems getting variables to inherit, or at least accessing local inherited variables in member functions.

Can anyone identify some changes that will make this OOP test code work?