Excel VBA Error #1004 – Excel cannot access the file

This is primarily a PeopleSoft nVision post – but it also pertains to Excel developers.  For those not familiar with it, nVision is a wrapper provided by Oracle/PeopleSoft whereby the Excel application can be used by PeopleSoft processes.  What gets produced is an Excel workbook.

Excel is installed on an application server, and is called via the nVision wrapper.  A number of our nVision layouts (Excel workbooks) have VBA macro code associated with them.

A shift in providing reports to consumers was recently made within the company.  Up til recently the reports were available from shares on the application server where nVision/Excel was running.  That’s been changed – the reports now have to be made available on a separate file server share.

And to make things both simpler as well as complex, the older style UNC path would no longer be allowed; instead all paths have to be DFS pointers.

Our users started running into random problems shortly after the change.  The common error was:

Error Source: Microsoft Office Excel.  Error #1004 – Description: Microsoft Office Excel cannot access the file ‘some file name’. There are several possible reasons:

The file name or path does not exist.

The file is being used by another program.

The workbook you are trying to save has the same name as a currently open workbook.

VBA Help Message # 1001004.

I was able to pin point what code was throwing the error, and it was in a section that does the following:

  1. Create a new workbook from a template
  2. Save the new workbook with a unique file name
  3. Copy some text from the source workbook
  4. Paste it into the new workbook
  5. Run some more vba to make the new worksheets pretty
  6. Save the new workbook and close it out

Rinse and repeat another several hundred times.  It took a couple of tries but from what I determined the error would always get thrown when attempting some action on the new (target) workbook.  And since that workbook was now being created in a remote share, DFS was the culprit.

That is a reasonable assumption based on how DFS works.  That’s not a topic for this post – if you want more Microsoft has an article here.  Note this line from the link – DFS requires Domain Name System (DNS) and Active Directory replication are working properly.

I see DNS and I think HTTP, network packets, domain controllers and RPC.  A far too complex environment for VBA to be operating in.

So to resolve the issue I changed where the work was being done.  Instead of saving the new workbook over the wire to the final destination and then doing more work to it via VBA; the work is back to being done in the same place the source workbook is.  That path is guaranteed by getting the ThisWorkbook.Path value of the source workbook.

So the above list is back to getting accomplished locally.  Once step 6 is complete there are two more items to the task list:

  • Use FIleSystemObject method CopyFile - and put a copy of the new workbook in the new reports share using DFS
  • Then user FileSystemObject method DeleteFile to get rid of the local copy of the new workbook.

No more random errors and the users are back to being happy.  And company policy is maintained.

Excel VBA – Execute macro code in another workbook

File this in the realm of why would I ever do that – then maybe after I explain you’ll see it makes sense.

I do this in situations where I’m ‘exploding’ data into reports.  And while this is more of a PeopleSoft nVision trick, I don’t see why it wouldn’t be useable in other applications.

Let me set up the scenario.  I have a chunk of data dumped into a workbook - I’m going to call it wbSource.  Inside that workbook is a macro that is going to run thru a worksheet and select a section of it based on some value in a column.

I copy and then paste the subset of data into another worksheet.  Nice, but I want it in another workbook.

Okay.  A bit of work here, I create another workbook and use it as a template.  That workbook has whatever base formatting I want along with macro code of its own.

Inside my wbSource I have the following code:

Private Function CreateTargetWorkbook() As Workbook

Dim wbTarget As Workbook
Set wbTarget = Workbooks.Add()
wbTarget.Activate
ActiveWorkbook.SaveAs Filename:=, FileFormat:=FileFormatNum
Set CreateTargetWorkbook = wbTarget
Set wbTarget = Nothing
End Function

The above function gets called this way:

Dim wbTarget As Workbook
Dim strRunCommand as String
Set wbTarget = CreateTargetWorkbook

I do my copy and paste code here…


strRunCommand = “‘” &  & “‘!Report_Main”
Application.Run strRunCommand

The italics make it a bit hard to read.  The string you create has a single quote surrounded by double quotes, the fully qualified path and file name, then another double quote, a single quote, an exclamation point, then the name of the macro that gets run followed by an ending double quote.  That gets added as a parameter to the Application.Run command.

Once the called macro code finishes control is passed back to the code in the source/caller workbook.

Now about why I go thru this.  First of all it follows good programming practice in that this follows the Principle of least privilege.  Code that knows how to section and subsection data is now separate from code that knows how to beautify a worksheet.  It also makes it easier to debug.  And later if changes are needed to the way the page is displayed, you don’t take a chance of breaking the code that chunks thru the data.  Vice versa if a change in terms of data occurs.

PSUNIT – a few odds and ends

This is a quick follow-up to the earlier posts I’ve made about PSUnit.  To get more familiarity with the tool I had started to build tests against a piece of a project I had just finished up and moved into production.

I was confident the code in the project was good as I had run test files against it continuously as I was coding.

A PSUnit test found a bug.

Ouch.  Glad I found it and not someone else, and it’s good to have found it now while other parts of the project are still outstanding.  And I’m kicking myself for not having used the PSUnit tool while I was writing the code for the project.

One more thing.  I’ve zipped up a project based on the code provided in the readme file you get if you install the PSUnit tool.  It’s available here.  I created it going thru the readme step by step – the code in the zip file is the result.  It was built using PTools 8.51.

PSUnit – Adding Tests

In my previous post I showed the various Assert tests that come with the PSUnit project.  I decided to add another test to the code.

There is only a single boolean Assert test – which checks if the value is True.  But there are times when a boolean False is the correct response.  So I added an AssertFalse test to the code:

AssertFalse(&isTrue As boolean, &onFail As string);

If the value in &isTrue is True, then the test fails.

Clearly you need to have pulled the PSUnit project into a PeopleSoft database instance and created the tables.  From here, start App Designer and open the TTS_UNITTEST Application Package.

You want to click on the TestBase app class and view the PeopleCode associated with it.

In the class TestBase I added the method definition:

  • method AssertFalse(&isTrue As boolean, &onFail As string);

Then I added the code for the method:

/* This was added to test for boolean False values */
method AssertFalse
   /+ &isTrue as Boolean, +/
   /+ &onFail as String +/
  
   If (&isTrue) Then
      throw create TTS_UNITTEST:Exceptions:AssertFailed(&onFail);
   End-If;
  
end-method;

How is this useful?  Let’s take an example of checking for a valid emplid.  I have a method:

method isEmplidValid
   /+ &empID as String +/
   /+ Returns Boolean +/
   Local boolean &_rtn = False;
   Local string &_msg;
   Local SQL &_sql;
  
   &_sql = GetSQL(SQL.VALID_EMPLID_CHECK, &empID);
   While &_sql.Fetch(&_msg)
      If &_msg = “X” Then
         &_rtn = True;
      End-If;
   End-While;
  
   &_sql.Close();
  
   Return &_rtn;
  
end-method;

The SQL definition is fairly simple:

SELECT ‘X’
  FROM PS_JOB A
 WHERE A.EMPLID = :1
   AND A.EFFDT = (
 SELECT MAX(A1.EFFDT)
  FROM PS_JOB A1
 WHERE A1.EMPLID = A.EMPLID
   AND A1.EFFDT <= SYSDATE)
   AND A.EFFSEQ = (
 SELECT MAX(A2.EFFSEQ)
  FROM PS_JOB A2
 WHERE A2.EMPLID = A.EMPLID
   AND A2.EFFDT = A.EFFDT)

This method validates emplids against the JOB table.  A return of False is a correct data state in this instance.  The Assert test would throw an error even though I should expect some values to return as false.

Next I create the tests.  I have two arrays – one has valid emplids for the organization; the other has invalid emplids.  I can now do both positive and negative testing with this method:

method TestIsEmplidValid
   %This.Msg(“TestFieldsCheckField: TestCheckChars”);
   Local boolean &rtn;
   Local integer &i;
   &rtn = False;
   Local PKGE:EMPLOYEE:CheckEmplid &target = create PKGE:EMPLOYEE:CheckEmplid();
  
   /* First the positive test */
   For &i = 1 To &_EmplidArray.Len;
      %This.Msg(“TestIsEmplidValid: Assert Test Value: ” | &_EmplidArray [&i]);
      &rtn = &target.isEmplidValid(&_EmplidArray [&i]);
      %This.Assert(&rtn, “Assert method failed”);
   End-For;
  
   /* Then the negative test */
   For &i = 1 To &_BadEmplidArray.Len;
      %This.Msg(“TestIsEmplidValid: AssertFalse Test Value: ” | &_BadEmplidArray [&i]);
      &rtn = &target.isEmplidValid(&_BadEmplidArray [&i]);
      %This.AssertFalse(&rtn, “AssertFalse method failed”);
   End-For;
  
end-method;

Having the AssertFalse method allows me to confirm that my checking routine is working correctly.  I’m able to test that my program can gracefully handle invalid/incorrect data.

PSUnit Assert Tests

PSUnit provides a series of Assert tests.  In the article provided as part of the zipped download Jim Marion goes step by step into the process of creating a test.  However he only uses a single test: AssertStringsEqual.

I dug into the code and listed the tests you can do with PSUnit.

Assert(&isTrue As boolean, &onFail As string);

If the value in &isTrue is False, then the test fails.  From the program notes:

The first argument must be a boolean expression, which should evaluate to true.  If false, PSUnit throws an exception to indicate that the test failed.  The test runner catches the exception, marks the test as having failed, and continues on to the next test.

AssertStringsEqual(&str1 As string, &str2 As string, &onFail As string);

AssertStringsDiffer(&str1 As string, &str2 As string, &onFail As string);

AssertNumbersEqual(&num1 As number, &num2 As number, &onFail As string);

AssertNumbersDiffer(&num1 As number, &num2 As number, &onFail As string);

AssertDatesEqual(&date1 As date, &date2 As date, &onFail As string);

AssertDatesDiffer(&date1 As date, &date2 As date, &onFail As string);

AssertRowsetValuesEqual(&rs1 As Rowset, &rs2 As Rowset, &onFail As string);

Method first checks the ActiveRowCounts between the two rowsets.

Then the method tests that both rowsets come from the same Record.

Finally the method tests the fields in each row of each rowset for equality.

If an Assert test fails, the exception text which includes whatever message you pass on as part of the variable  &onFail gets sent to Class AssertFailed; which then calls the PeopleCode function CreateException.

PeopleSoft PSUnit

I first came across PSUnit in Jim Marion’s book PeopleSoft PeopleTools Tips & Techniques.  It’s a different tool from Test Framework – and you should consider it as complementary to PTF.

Jim has a write up of it here; there is another small explanation of it here.  Both articles give a link to the code, or you can get it here.

PSUnit is a Test Driven Development tool.  With Test Framework you code, create a page, and then put your page into a component.  The component gets applied to a menu which then get set into the registry.

With PSUnit you create a test framework Application Package, which gets plugged into an already existing test page.  Better yet – while Test Framework can help to point out where a transaction throws an exception, PSUnit lets you dig further and find out why.

From Jim Marion’s blog piece PSUnit Unit Testing Framework:

You, the developer, receive a notification from a user that page X of component COMP_X is calculating the wrong values. The user informs you that the calculation and error occur when he/she clicks save. From this information, you speculate that the calculation happens in the SavePreChange or SavePostChange event of the component or some record used in the component. Unfortunately, you are not familiar with this page or component.

With a PeopleCode trace, you are able to identify six potential events. You notice that these events call FUNCLIB’s and App Classes creating a horrendously deep call stack. From what you have in front of you, it is obvious that a quick review of this 3,000+ line trace file won’t provide an easy solution.

At this point you have several options:

Continue to treat COMP_X as a black box, investigating it from the outside.

Dig into the code and speculate as to its purpose.

Configure app server debugging and step through the deep call stack.

Start adding MessageBox statements to the delivered code so you can interrogate the state of the application as it runs.

We will choose the final option, the MessageBox option. Yes, this will require us to modify delivered code, but this modification should have no impact on the behavior of the code. The modification doesn’t concern me as much as forgetting to delete one of those MessageBox statements after I find and fix the problem. And then, once I find the correct combination of MessageBox statements to show the problematic data or logic, I hate to delete them, knowing I may have to visit this code at a future date (sooner then I want, but far enough in the future that I’ve already forgotten how I solved the problem). Wouldn’t it be nice if, once you found the appropriate combination of logging statements, you could just leave them in the code?

You should read the entire post.  I’ll list the various Assert tests that are available in another post.

More fun with Application Packages – Instances

In my last post I had made this statement:

Instance variables are like Static variables in Java.

Hat tip to Helena who provided insight:

One comment though – instance variables are not static variables (in terms of scoping rules, one the same private instance variable is not shared by multiple instances of the class); they are in fact instantiated for each instance/object of the class.

So if I have a class definition ClassDef, with 1 private instance variable &InstanceVar, and I instantiate 2 objects of type ClassDef, I will have 2 instances of &InstanceVar in memory, not just 1.

This contrasts with static member variables in Java, where the variable is shared and in the example above, only 1 instance of &InstanceVar would have been allocated in memory.

Good point – so lets dig into this a bit – as others have here and here.

Since I made the statement like Static variables in Java let’s look at what those are.  From Oracle’s Java Tutorials on Understanding Instance and Class Members:

When a number of objects are created from the same class blueprint, they each have their own distinct copies of instance variables. In the case of the Bicycle class, the instance variables are cadence, gear, and speed. Each Bicycle object has its own values for these variables, stored in different memory locations.

Sometimes, you want to have variables that are common to all objects. This is accomplished with the static modifier. Fields that have the static modifier in their declaration are called static fields or class variables. They are associated with the class, rather than with any object. Every instance of the class shares a class variable, which is in one fixed location in memory. Any object can change the value of a class variable, but class variables can also be manipulated without creating an instance of the class.

I added the bolding and underlining in the above.  So as Helena pointed out, in Java the same memory location is used by every instance of the class having a variable defined as static.  Each instance of a class gets a reference (having been weaned with C I would say pointer but a Java purist would start throwing acorns at me) to the location in memory where the value actually resides.  Which falls in line with how memory allocation works in Java.  Java stores objects on the heap, variables sit on the stack.  But variables are ‘merely’ pointers/references to the objects sitting on the stack.  Enough teasing – I also know there are differences between a pointer and a reference – but that is a C++ convention, not C.  In any event, it’s efficient for Java to have Static variables work this way.

PeopleBooks provides this tidbit in Declaring Private Instance Variables:

A private instance variable is private to the class, not just to the object instance. For example, consider a linked-list class where one instance needs to update the pointer in another instance. Another example is the following class declaration:

class Example private instance number &Num; end-class;

A method of Example could reference another instance of the Example &Num instance variable as:

&X = &SomeOtherExample.Num;

Avoid making every instance-scoped variable a public property. You should consider each variable individually and decide if it belongs in the public interface or not. If it does, decide if the variable warrants get or set modifiers and therefore should be a public property. If the variable only serves internal purposes to the class, it should be declared as a private instance variable.

Again, I added bolding and underline.  But note the word pointer - a double plus unJava word.  So lets look at a language that does use pointers.

I’m a pack rat.  I don’t throw books away.  So I looked in my collection and grabbed my copy of Deitel & Deitel C++ How To Program:

Each object of a class has its own copy of all the data members in the class.  In certain cases only one copy of a variable should be shared by all objects of a class…  A static class variable represents “class-wide” information. 

Let us motivate the need for static class-wide data with a video game example.  Suppose we have a video game with Martians and other space creatures.  Each Martian needs to be brave and willing to attack other space creatures when the Martian is aware that there are at least 5 Martians present.  If there are fewer than 5 Martians present, each Martian becomes cowardly.  So each Martian needs to know the martianCount.  We could endow class Martian with martianCount as a data member.  If we do this, then every Martian will have a separate copy of the data member and every time we create a new Martian we will have to update the data member martianCount in every Martian.  This wastes space with the redundant copies and wastes time in updating the separate copies.  Instead, we declare martianCount to be static.  This makes martianCount class-wide data.  Every Martian can see the martianCount as if it were a data member of the Martian, but only one copy of the static martianCount is maintained by C++  This saves space.  We save time by having the Martian constructor increment the static martianCount.  Because there is only one copy, we do not have to increment separate copies of martianCount for each Martian object.

Hmmm.  Something fishy here.  Both C++ and Java are using static variables the same way.  Let’s look at PeopleSoft some more.  There is some code here that bolsters what Helena had pointed out.  The instance in an App Package class gets instantiated as its own distinct block of memory – so it breaks the notion and value of having a C++/Java type static variable.  However it’s able to be referenced and changed by another instance of the same class.   So take the less efficient part of the Deitel explanation and there you have it.

To my mind this is bordering on an architectural bad smell of connector-envy, and can lead to some code smells on the part of development.

Defining and Using Constants with PS Application Package

I’ve used Application Packages more and more after reading about them in Jim Marion’s PeopleSoft PeopleTools Tips & Techniques.  And I like using them far more than creating functions in a FUNCLIB_ library.

I’ve got an App Engine program I’m developing, and I’m using an App Package class for error handling.  I’ve a small list of error codes that get sent by the exception handler routine and those codes are used to get a description.  I could use message catalog for the texts of course, but in this case I’m going to be lazy and keep the values in the code.  This is for a batch process that will be scheduled to run nightly; it isn’t customer facing.

To avoid having magic numbers appear in my code I wanted to define a set of constant integer values in the App Package class.  PeopleBooks gets a bit obtuse on this subject though.

So, let’s go thru the exercise of creating them, then how to use them.

In the class definition I create a private constant:

private
Constant &INVALID_EMPLID = 1;

So far, so good.  any methods inside the class can use that value:

Evaluate &errCode
When = &INVALID_EMPLID
&msg = “Invalid emplid provided.”;
Break;

But I want the code throwing the exception access to the same constant.  PS App Package definitions are – well – eccentric.

Java, C++ and C# class structures look similar.  You define the class, then add fields if needed, and the methods of the class.

App Packages have methods, but then bring in the idea of properties and instances as well as Constants.

A property is exactly that, it’s a property of the instantiated object from the class – it’s the Has A of the object.  As in my class House Has A property of RoomColor.  PeopleBooks provides an explanation for a property as an attribute of an object.

Instance variables are like Static variables in Java.  An instance is private to the class, not just to the instantiated object.

Which gets us nowhere in terms of having our constant value used in my exception handling – yet.

Here is the key part – PeopleSoft set up properties to take the place of creating get and set methods.  They consider it more efficient to declare a property (which has no parameters) than to use a method to do get/set routines.

So instead of having a method:

method getSomething() as integer;

You would instead declare a property:

property integer mySomething get;

This was the long way around to explain how I get to use my Constants definition.  You saw above where I created a constant for &INVALID_EMPLID.

I declare a public (this has to be public – PS will bark at you if you try to do anything else with it) property – making sure it has a get as part of the definition:

property integer invalidEmplid get;

Then you write a get routine:

get invalidEmplid
/+ Returns Integer +/
Return &INVALID_EMPLID;
end-get;

Now my App Engine code can access that constant value - assuming that I’ve declared the App Package Class inside the code:

&errnum = &err.invalidEmplid;

If I find later on that I want to change the value &INVALID_EMPLID points to, I only have to do it in one place.  Less code maintenance, which is the real value of not using magic number coding.

Extending PeopleSoft FTPClient App Package Class

This post will be covering a few items under the same topic.

We ran into problems with the built in FTP PeopleCode functions with 8.51.  So for example, to use GetAttachment, one of the parameters you are to supply is URLDestination, which would resolve to something like:

ftp://anonymous:hobbit1@ftp.ps.com

Where anonymous is the user name, and hobbit1 the password.

If you are in an Active Directory situation, and the domain needs to be a part of the username:

<domain name>/<user name>

With tools 8.51 that slash throws an error.  So to resolve this we stopped using the built-in functions, replaced them with calls to the supplied HCSC:FTP:CLIENT:FTPClient Application Package/Class.

The class FTPClient calls an open source netcomponents.jar file, provided by www.savarese.org.

There is a problem with the delivered app package however, the developers never allowed for the FTP return codes.  I’m providing a simple fix. While I was at it, I added FTP rename and delete functionality.

I created an App Package, then added a new class with the methods I wanted:

class FTPClientExtended extends HCSC:FTP:CLIENT:FTPClient
/** Constructor*/
method FTPClientExtended();
/*
Returns the integer value of the reply code of the last FTP reply.
You will usually only use this method after you connect to the FTP
server to check that the connection was successful since connect is of type void.
*/
method getReplyCode() Returns integer;

/*
Returns the entire text of the last FTP server response exactly as it was received,
including all end of line markers in NETASCII format.
*/
method getReplyString() Returns string;

/*
Renames a remote file.
Parameters:from – the name of the remote file to rename.
to   – the new name of the remote file.
Returns:True if successfully completed, false if not.
*/
method rename(&from As string, &to As string) Returns boolean;

/* Deletes a file on the FTP server.
Parameters:pathname - The pathname of the file to be deleted.
Returns:True if successfully completed, false if not. */
method deleteFile(&pathName As string) Returns boolean;

protected

/** holds reference to Java ftp object */
property JavaObject _ftp;

end-class;

Note the extended keyword.  This class is now a subclass of the delivered FTPClient.

The constructor does the heavy lifting for us:

/**
Constructor
*/
method FTPClientExtended

/* Create the base class constructor */
%Super = create HCSC:FTP:CLIENT:FTPClient();

/* create pointer to Base class Java object */
&_ftp = %Super._ftp;

end-method;

We create Superclass references to the class and the base class Java object.   Take a look at the delivered FTPClient Application Class constructor:

method FTPClient

/* Create the base class constructor */
%Super = create HCSC:COMMON:BASE:JavaBase(“com.peoplesoft.hr.hr.ftpclient.ExFTPClient”);

/* create Java object for splitter */
&_ftp = %Super.getJavaObject();

end-method;

The base class FTPClient is iteslf using Superclass references.

The rest gets very straight foward:

method getReplyCode

/+ Returns Integer +/

/* Return the FTP code – use to determine if failed or successful */

Return &_ftp.getReplyCode();

end-method;

method getReplyString

/+ Returns String +/

/* Returns the entire text of the last FTP server response exactly as it  was received, including all end of line markers in NETASCII format.  */

Return &_ftp.getReplyString();

end-method;

method rename

/+ &from as String, +/

/+ &to as String +/

/+ Returns Boolean +/

Return &_ftp.rename(&from, &to);

end-method;

method deleteFile

/+ &pathName as String +/

/+ Returns Boolean +/

Return &_ftp.deleteFile(&pathName);

end-method;

By creating a new Package and class, I’ve added functionality but without having to customize the delivered code.  Come upgrade time this is (hopefully!) going to be a lot easier to deal with.

Beware the widget

The Jabberwock, as illustrated by John Tenniel

 “Beware the Jabberwock, my son!

The jaws that bite, the claws that catch!

 Beware the Jubjub bird, and shun The frumious Bandersnatch!”

 So, I wanted a simple drop down list so a tester/player could pick a scene and then go there.  I didn’t find what I wanted, but there was this nice feature of the Corona Widget object library called the newTableView:

 Corona tableView widget

Looks good, maybe more complicated than what I need but the code looks straight forward (okay, not as easy and straight forward as old school classic VB 6 – but not as weird and hard as Visual C++ MFC of the same era – and once again I’m dating myself…)

The demo’s I found here and here provided the basics – but!  I need to incorporate this inside the Corona Storyboard construct.  And that is where the fun and games began…

Now a mea maxima culpa is in order – what follows is probably due to my being overzealous in getting rid of memory issues.

I created two arrays – one is a straight forward array with the names of the scenes in order that I want to provide.

The second is an array of arrays used by the tableView object.  One of the weaknesses in using Corona is the documentation is sparse and terse – just enough to get you into trouble – but the stuff you really need to know is found in the forums. From what I’ve figured out is the row construct in the list allows you to have a picture object, a title and then descriptive text. There may be more, but this is far more at this point than what I really need.  Hence an array of arrays – or to use the Lua way of thinking – a table with individual rows that could contain a number of fields (columns) greater than one.  Let’s move on.

 He took his vorpal sword in hand:

Long time the manxome foe he sought—

So rested he by the Tumtum tree,

And stood awhile in thought.

 Got my lists, got my tableView, and wow – it actually displays what I want!

It’s just that the damn thing crashes when I do a selection.  This one got me.

And as in uffish thought he stood,

The Jabberwock, with eyes of flame,

Came whiffling through the tulgey wood,

And burbled as it came!

So I unsheathed my vorpal sword – er, I started to really use the Lua Glider debugger.  Need to go back a bit here.  In my desire not to create any more memory leaks I had made sure in the storyboard function scene:exitScene I set any variable I declared to nil.  And that was the source of my errors.

One, two! One, two! and through and through

The vorpal blade went snicker-snack!

He left it dead, and with its head He went galumphing back.

The errors were just – weird.  Didn’t make sense.  And here is where using Lua Glider saved the day (used as my vorpal blade).  I set a break point for the listener function in my code – the code that gets fired when a user clicks on a selection in the list.

And as I expected the code worked perfectly – selecting the correct item in the selection array based off the event index.  But then we went down the rabbit hole…

It turns out after all of that the storyboard code kicked in.  The exitScene code got called – setting all of my variable to nil.  Oh – and then the listener function got called again – and since everything had just been set to nil it set off errors – oh my…

Okay, I’m sure my code isn’t the most efficient at this point.  Why the listener function is getting called twice I can’t answer.  However I did learn a valuable lesson here.

“And hast thou slain the Jabberwock?

Come to my arms, my beamish boy!

O frabjous day! Callooh! Callay!” He chortled in his joy.

 ‘Twas brillig, and the slithy toves

Did gyre and gimble in the wabe;

All mimsy were the borogoves,

And the mome raths outgrabe.

Clearly, at this point in my Lua/Corona development the ONLY stuff I should be setting to nil (null) in the storyboard scene:exitScene function are those objects that get inserted into the display view/self view group.  Anything else – well as the maps used to say here be dragons

Cross posted at my other blog SE Studio Team C

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