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Although Personal Stock Streamer already has a built-in capital gains report, I took it upon myself to rewrite it in VBScript not only to prove that it can be done, but to extend it and make it easily customizable.

Normally, calculating capital gains for a given ticker would require applying each transaction checking whether it generated a change in position, and whether that position actually generated capital gains.  For example, a simple buy transaction may not generate capital gains, but a sale transaction may generate a gain or a loss if there is an open long position. This type of processing is already done internally within Personal Stock Streamer to calculate gains and losses, and to duplicate this in script would require a lot of work.  Getting this functionality for free is one advantage of having the capital gains report embedded in the main application.

So for this extension I had to cheat a little bit: I modified the script plug-in in Personal Stock Streamer 7.1 to expose the functionality described above, so that it would be trivially simple (and much faster) to rewrite the capital gains report in script.  This also eliminated the need to duplicate the transaction processing logic that is already inside Personal Stock Streamer.  What I did is add an optional argument to the Ticker::ApplyTransactionToCurrentHoldings() and Ticker::ApplyTransactionsToCurrentHoldingsUntil() methods that allows you to pass a reference to a callback object.  This callback object would define a handful of methods that would be called at the appropriate time by the main application, and all the report had to do was gather and summarize the data.  In the case of this report, the callback object is the same object that the report is running in, so I just pass "me" as the argument.

Before I go into describing these callback methods, I should say something about the design of the handler class for this report.  In order to separate out the long-term gains, short-term gains, and other income and expenses, I created three arrays that get populated with summary data by the callback methods I am about to describe.  This neatly separates the processing and output code, which allows easy modification of the formatting code to get any style of report you need.

The report handler defines four callback methods.  The first two, OnCBAddHoldings and OnCBSubtractHoldings, are called by Personal Stock Streamer whenever a transaction affects the current holdings for a ticker.  Because not all transactions that affect holdings are related to the capital gains report, there is a quick check at the beginning of each method to make sure that only certain transactions get saved in the summary arrays.  The second two callback methods, OnCBAddIncome and OnCBSubtractIncome, are called for dividends, income, and expense transactions that do not affect the holdings.  This allows us to put together a nice summary of those transactions as well.  There is absolutely nothing complicated about these callback methods because all they do is store the summary data for later.

After the processing is finished, the output method is called once for each of the three sections of the report, which sorts the array by ticker and generates the HTML output that is displayed in the Reports view.  One possible enhancement that could be made in a future version of this report is to have sub-totals for each ticker to make it easier to see the gains for individual investments.

The full source code for the Capital Gains report is available here.

The reports you see in Personal Stock Streamer are simple HTML documents that are generated and formatted by the reporting engine. The built-in reports (capital gains, etc.) are written in C++ and compiled into Personal Stock Streamer, but with the new Personal Stock Streamer 7.0 software it is possible to create custom reports completely in script. For this example, we will create a YTD performance report that shows the difference between the current price of a stock and the price at the beginning of the year.

Assuming you have read the Introduction to Personal Stock Streamer Extensions article, we can jump right into defining the report class.

The report handler class has just one required callback method, GenerateReport(), that will be called by the report generator engine when you select your report from the reports list.

class PriceReportHandler

	' create the report
	public Function GenerateReport ( Name, Handler, Folder )

	end Function

Because multiple reports can have the same handler class, the GenerateReport() method is passed the Name of the requested report so that your code can differentiate between multiple reports. The second argument, the Handler object, is what you will use to get the report parameters and to generate the report. The Folder object is the current folder or portfolio over which the report should be generated.

Since reports are just simple HTML documents, we can start by sending the header to the reporting engine.

' generate report		
Handler.WriteReport "<body bgcolor=White>"
Handler.WriteReport "<b>Price Performance Report for " + Handler.FilterPeriod + "</b>"
Handler.WriteReport "<table border=0 cellpadding=0 cellspacing=10>"
Handler.WriteReport "<tr><th><b>Symbol</b></th><th><b>Starting Price</b></th><th><b>Ending Price</b></th><th><b>Gain</b></th><th><b>% Gain</b></th></tr>"

As you can see, this report uses the Handler.FilterPeriod property to show the user what the selected filter period is. The filter period will be the same as what is selected in the Reports tab.

Now we are ready to write the report:

RecurseFolder Handler, Folder

Handler.WriteReport "</table></body>"

Unfortunately we don't get anything for free here. Because portfolios and folders may themselves have nested folders, we must define a RecurseFolder method to go through all of them and generate the report. The last line then writes the end of the table and finishes the report.

So now we have to write the RecurseFolder method, which is the most complicated method in this class.

public Function RecurseFolder ( Handler, Folder )
	' process the tickers in the folder
	Set Tickers = Folder.Tickers

	For i = 1 To Tickers.Count

We start by getting the tickers from the folder and iterating over the collection using the For statement. For each ticker we must retrieve the historical data for the requested date range (ie. the current year) and calculate the difference between the price at the end of the range vs. the price at the beginning of the range.

' get the history data for this year
Tickers.Item(i).SetProp "HistoryStart", Handler.FilterDateStart
Tickers.Item(i).SetProp "HistoryEnd", Handler.FilterDateEnd

Set History = Tickers.Item(i).HistoryData

We are again using properties of the Handler object to get the start and end of the date range requested by the user. Then we retrieve the historical data for that range.

If Not History Is Nothing And History.Count > 0 Then

Here is a little complication. What if the historical data for that range is not available or has not been retrieved yet? We will handle this shortly, but first we handle the case where we do have the data.

BeginValue = History.Item(0).GetProp("Close")
EndValue = History.Item(History.Count - 1).GetProp("Close")

Diff = EndValue - BeginValue
DiffPct = ((EndValue - BeginValue) / BeginValue) * 100

This case is easy. We get the data at the beginning and end of the range and calculate the difference. Then we can write the report:

Handler.WriteReport "<tr><td>" + Tickers.Item(i).GetProp("Symbol") + "</td>"
Handler.WriteReport "<td align=right>" + FormatNumber(EndValue,2) + "</td><td align=right>" + FormatNumber(BeginValue,2) + "</td>"
Handler.WriteReport "<td align=right>" + FormatNumber(Diff,2) + "</td><td align=right>" + FormatNumber(DiffPct,2) + "</td></tr>"

This produces a formatted table filled in with all the right values. There is a case that is not handled by this code, and that is what if only partial data is available for the date range? Because Personal Stock Streamer expires the historical data cache each day, this case would not occur and therefore does not need to be handled explicitly.

Now we can handle the case where no historical data is available for the range:

Else
	Handler.WriteReport "<tr><td>" + Tickers.Item(i).GetProp("Symbol") + "</td>"
	Handler.WriteReport "<td align=right>Waiting for Data</td>"
	
	Tickers.Item(i).DownloadHistoryData Handler.FilterDateStart, Handler.FilterDateEnd
End If

Basically what we are doing here is putting up a "Waiting for Data" sign and requesting historical data for the report range through the Ticker object. This request will happen asynchronously, so somehow we will need to handle it. I will explain this part shortly, but first we need to finish up this method:

	Next
	
	' recursively loop through the subfolders
	Set Folders = Folder.Folders
	
	For i = 1 To Folders.Count
		RecurseFolder Handler, Folders.Item(i)
	Next
	
end Function

This code finishes out the For loop, then recursively calls itself for any nested folders.

Now we get to a little complication. Although the report handler class only has one required method, we need to handle the case where the historical data request was sent to Personal Stock Streamer but the data actually arrives at a later time. Fortunately Personal Stock Streamer provides a way to handle this case by registering interest with the event manager. If I may jump ahead a little bit to show part of the initialization code for this extension:

Set EventManager = Application.GetObject("EventManager")

If Not EventManager Is Nothing Then
	EventManager.RegisterHandlerMethod ReportHandler, "OnHistoryUpdated"
End If

This is where we hook up our report handler class to the OnHistoryUpdated event that tells us when historical data has arrived for a ticker. Since we register for this event we must now define an OnHistoryUpdated method in the report handler class:

public Function OnHistoryUpdated ( Ticker )
	If (Application.GetCurrentView() = "Reports") Then
		Set EventManager = Application.GetObject("EventManager")
		EventManager.RegisterHandlerMethod me, "OnAppTimer"
	End If
End Function

Why aren't we updating the report here? Because OnHistoryUpdated will be called once for each ticker, if you are requesting historical data for multiple tickers at once you could be needlessly updating the report once for each ticker. Instead what we are doing here is registering for yet another event to notify us when the 1-second application timer goes off. This allows us to delay recalculating the report by just a little bit until all of the historical data comes in.

So now we can define the OnAppTimer event handler.

public Function OnAppTimer
	EventManager.UnregisterHandlerMethod me, "OnAppTimer"

	Set ReportManager = Application.GetObject("ReportManager")
	ReportManager.UpdateCurrentReport
End Function

Notice that the first thing we do is to unregister the handler, which makes sure that the handler is not called more than once. Then the last thing is to force an update of the current report, which is done through the report manager object. Note that you can't call the GenerateReport method directly because in the OnAppTimer handler do you not have all of the information and extra objects needed for GenerateReport to work.

So that is the end of the report handler class, and we should not forget to end the class definition.

end Class

Because I already covered part of the initialization with registering for the OnHistoryUpdated event, here is the second part, actually registering the report:

Set ReportHandler = new PriceReportHandler
Set ReportManager = Application.GetObject("ReportManager")

If Not ReportManager Is Nothing Then
	ReportManager.Register "Price Performance", ReportHandler
End If

This is probably starting to look very familiar by now. We simply create an instance of the report handler and register it with the report manager.

That is the end of the custom report extension; the full extension code is available here.

So where do you go from here? The sky is the limit. With easy access to your porfolio data and extensive historical data you can now create as many custom reports as you need to help you with your investment decisions.