I am having trouble while running excel macros as it causes my UI to freeze.
Consider the following code:
Call Run_Test()
Sub Run_Test()
Set oQTP= CreateObject("Quicktest.Application")
oQTP.Open "<Test Path>"
oQTP.Run"<Test Path>"
End Sub
The problem here is that while running the above Run_Test method "oQTP.Run" takes some time to complete and during this time if click on excel sheet the UI freezes.
So is there any way i can run this method asynchronously and prevent the excel from freezing?
Or Is there any other technique to prevent this?
VBA itself does not provide any support for asynchronous programming. The programmer must explicitly call DoEvents within nested loops to allow the Windows Message Queue to be processed.
However, it is possible for a function library invoked by VBA to provide asynchronous calls. Classic ADO does by providing the option of specifying a query call as asynchronous, raising an event when the call has completed (either successfully or unsuccessfully).
If you require custom code to run asynchronously you will have to code it in an environment that provides such support, such as C# or VB.NET, and call into the resulting Assembly.
If your question is about running QTP asynchronously you can just specify False as the WaitOnReturn parameter of the Run method.
See this answer for further details.
Related
I've created a spreadsheet which optionally uses Bloomberg data pulled using the API COM 3.5 Type Library. I want to be able to distribute that spreadsheet to non-Bloomberg users, but they can't run it since they don't have the right libraries.
All blpapi-related code besides what's in the Class Module is behind if statements that should not be entered by the non-BB users. In the class module, I lazily define the session and Service so that the blpapi-specific definitions are delayed until the class initializes (see below):
Option Explicit
Private session As Object
Dim refdataservice As Object
Private Sub Class_Initialize()
' First create session.
Set session = New blpapicomLib2.session
session.QueueEvents = True
session.Start
' Then open service.
' A service provides the schemas needed to make requests.
session.OpenService "//blp/refdata"
Set refdataservice = session.GetService("//blp/refdata")
End Sub
In short - the code which appears to be causing the issues never runs. My (very limited) understanding of VBA is mostly functional, so I'm probably missing something obvious. Is this a compilation-related error? Is there a way for me to precompile the VBA so users don't experience this issue? Maybe some type of error handling method so the workbook doesn't hang?
Here was my solution for my own problem:
I had two functions with inputs that used library-specific types. I converted those to generic objects (using late binding on the session and refdataservice was not enough). Then, I unselected the bbcom library, and added a dynamic reference to the dll file in Workbook_Open(). Even if the load fails, the error is able to be caught, whereas before excel would have to be killed. This is still a problem if the user tries to use part of the workbook that uses the BB-related code, but this can be mitigated in a few different ways.
The setup
I'm developing and maintaining an Excel add-in that comes with its own tab of controls within Excel's Ribbon UI. I've come across the problem of state loss before (meaning loss of all variables with global scope, static variables, etc, which of course includes my reference to the RibbonUI). With regards to the ribbon reference I've "solved" the problem by including a "Reset Ribbon" button that restores the reference from a persistently stored pointer and then invalidates the ribbon. Although certainly not the most elegant, this part works just fine.
However, after the introduction of a logging class, the state loss issue haunts me once again. The logger is instantiated in ThisWorkbook's module:
Private Sub Workbook_Open()
Set LogToFile = SingletonFactory.getToFileLogger
End Sub
and is then put to work, for example, as follows:
Private Sub buttonReloadObjects_onAction(ByVal control As IRibbonControl)
LogToFile.trace "Event firing: buttonReloadObjects_onAction"
' more stuff happening...
invalidateRibbon ' restores ribbon object and invalidates it
End Sub
The logger is instantiated when the add-in is loaded so that I have the freedom to log whatever I want within the confines of my add-in's code. It has several logging levels like trace/debug/error/... and a couple of other methods. Usually it works just fine - until the state loss hits (usually caused by an unrelated error, followed by clicking "End").
State loss
At this point the VBA environment forgets about the very existence of my LogToFile object and nothing works any more, because every click on the ribbon controls will trigger a runtime error 91: Object variable or with block variable not set pointing to whatever line is the first to contain a reference to LogToFile.
A solution?
Now, short of doing crazy workarounds like placing
if not isObject(LogToFile) then
Set LogToFile = SingletonFactory.getToFileLogger
end if
LogToFile.trace "Message"
before any occurrence of LogToFile, the only real "solution" I was able to come up with is to wrap all my logger calls in functions (residing in a standard module) and call these functions any time I want to send something to the log. This way I could catch the missing object reference right before the object is needed and I avoid calling methods of uninstantiated objects.
However, after having everything neatly encapsulated in class modules, it strikes me as odd, maybe even wrong(?), going down this route.
So, is there a "proper" solution to the problem of a lost logger instance? Or is my suggested approach already as proper as it can get?
Note: This problem is of course not specific to logging classes. It affects all global variables, most notably my ApplicationEventClass. The issue just happens to be the most glaring with the logger due to its frequent usage around all entry points to the code.
You only need one function that either returns the original variable or resets it. If you call that function LogToFile you don't need to change any of the other code other than removing the Workbook_Open code which is then superfluous. So:
Function LogToFile() As WhateverVariableType
Static temp as WhateverVariableType
If temp is Nothing then Set temp = SingletonFactory.getToFileLogger
Set LogToFile = temp
End Function
This way you will also still benefit from Intellisense when writing the code.
Note: you may not actually need the temp variable - it depends on whether there are settings that you want persisted. If there are, you may want to reset them in the function too.
I'm using ExcelDNA to develop an XLL.
In it, I have a form living in a DLL to which I pass "ExcelDnaUtil.Application" as a member to facilitate interactions between the form and the instance of Excel running the XLL.
If I launch the form in the main thread using:
form1.show()
when I close the form then close Excel, Process Explorer shows that the Excel process is properly disposed of.
If I launch the form using a new thread:
Dim workerThread As Thread
workerThread = New Thread(Sub() form1.showdialog())
workerThread.Start()
when I close the form and then close Excel, the process remains in Process Explorer. I have been careful not to use two decimal points in any line of code and set the interface member to "nothing" when closing the form. I am not using "ReleaseCOMObject" as other articles have indicated that it is bad-practice.
Question: How do I dispose of the Excel process properly from a separate thread?
It's impossible to get the COM stuff right cross-thread.
You should never talk to the Excel COM object model from another thread. If you follow this one simple rule, you never have to worry about two dots, never have to set anything to Nothing and never have to call any of the ReleaseComObject hacks. And Excel will close nicely.
Since Excel is single-threaded (actually because the Excel COM object model lives in a Single-Threaded Apartment), there is no performance benefit from talking to Excel with another thread - internally it all gets marshalled to the main thread anyway.
If you dare to talk to Excel from another thread, then any COM call could fail, at any time. This is because Excel is still 'alive' and can go into a state where the 'object model is suspended', causing all COM calls to fail (with errors that even a COM message filter can't catch). When would Excel go into such a stubborn mode? When the user does something crazy like click their mouse button, for example.
How then to call back to Excel after you've done some work on another thread? Excel-DNA has a helper that will schedule work to be done back on the main thread, when Excel is in a mode where COM calls are safe. You just call ExcelAsyncUtil.QueueAsMacro(...) with a delegate containing the work to be done. This call can be made at any time from any thread, but the code will only run when ready.
A somewhat clumsy example is this:
Public Module MyFunctions
Dim workerThread As Thread
Public Function OverwriteMe() As Object
Dim caller = ExcelDnaUtil.Application.Caller
workerThread = New Thread( _
Sub()
Thread.Sleep(5000)
ExcelAsyncUtil.QueueAsMacro( _
Sub()
caller.Value = "Done!!!"
End Sub)
End Sub)
workerThread.Start()
Return "Doing it..."
End Function
End Module
I have a thread, called TAlertThread. The thread interacts with its owner by triggering events. For example, when certain data is available inside the thread, it sets some temp variables and calls Synchronize(UpdateAlert) which in turn triggers the appropriate event.
Now the thread works perfectly in any standard windows application. My problem is when I put that thread inside of an ActiveX form (TActiveForm). The ActiveX control (aka COM object) is then embedded inside of a Windows Desktop Gadget (via HTML / Javascript). I also have experience with this, the gadget is not the issue. The ActiveX component works fine in its destination, except the thread is never executed. It's even being called EXACTLY the same way as I called it from the App.
Is this some limitation with ActiveX, blocking threads from executing? I wouldn't think so, because other things that require threads internally (such as TADOConnection) work. I am in fact properly calling CoInitialize and CoUninitialize appropriately. Again, works perfect in an application, but does not work at all in ActiveX.
Here is how I call this thread...
procedure TRMPDashXS.ExecThread;
begin
//Thread created suspended
lblStatus.Caption:= 'Executing Thread...';
fThread:= TAlertThread.Create(fConnStr); //fConnStr = connection string
fThread.Priority:= tpIdle;
fThread.OnConnect:= Self.ThreadConnected;
fThread.OnDisconnect:= Self.ThreadDisconnected;
fThread.OnBegin:= Self.ThreadStarted;
fThread.OnFinish:= Self.ThreadFinished;
fThread.OnAlert:= Self.ThreadAlert;
fThread.OnAmount:= Self.ThreadAmount;
fThread.Resume; //Execute the thread
end;
I suspect this might describe exactly what you're experiencing in your version of Delphi:
http://soft-haus.com/blog/2009/02/10/codegear-borland-activex-threading-synchronization-problems/
which references the same article you cited:
http://edn.embarcadero.com/article/32756
I'm not sure if that helps ... but I hope it does. At least a little :)
PS:
Is there any particular reason you have to use Com/ActiveX and/or TActiveForm?
According to this article here: http://edn.embarcadero.com/article/32756 web browsers don't allow threading via ActiveX. However that still doesn't explain why it doesn't work when I put it in a C# application.
I am developing a Windows forms application which connects to a piece of hardware, acquires a lot of data (~1 GSample/sec), processes it, and spits it out to the screen upon a button click. I am now trying to automate the process in a loop that can be started/stopped at any time so I can monitor it whilst tweaking the input to the acquisition hardware. I thinks it's clear that I need to do this on a separate thread, but I'm having a heck of a time trying to do this in c++/cli - I have found a number of good examples using MFC, which is not supported by Express.
Specifically: My task is to press a button which is handled in Form1.h, to call a function in my main file Acquisition.cpp which contains the following code (currently an infinite loop)
void Form1::realTimeUpdate()
{
// live is a boolean variable set by a button on the form
while(live)
{
displayVariance(getVar(getQuadratures(100),nbrSamples));
}
}
I wish to execute this code in a separate thread so that the main program can listen for the user request to stop the operation. Without threading, I currently have to forcefully quit the program (or set it to run a fixed number of times) to stop it.
Is there any suggestions how I might go about running this code on a separate thread?
I've (unsuccessfully) tried a few things already:
Modifying the example given in This Microsoft Example. Problem: requires /clr:oldSyntax option which is incompatible with the other 1300 lines of code in the program.
Trying to do what I'd do in Java (Declare a global thread and start/stop it from any point in the code. Problem: Compiler won't let me declare a global System::Threading.Thread
this beautiful example. Problem: Requires MFC.
Any suggestions would be greatly appreciated!
You can use a BackgroundWorker or a Thread to handle this. You'll need to make sure that the portion of your work that updates the UI is marshaled back to the UI thread, however.
Here is a tutorial on threading in C++/CLI.
For the record, upon Reed's suggestion about using a BackgroundWorker, I sifted through the code at the bottom of this page and modified my code so that:
It created a new backgroundWorker BGWorker in which BGWorker->DoWork() called my realTimeUpdate() function.
A button on the main Form calls either RunWorkerAsync() or CancelAsync() depending on whether or not the process is running (checked by a boolean flag in my main program).
The realTimeUpdate() function is now passed a BackgroundWorker - realTimeUpdate(BackgroundWorker^ worker, DoWorkEventArgs ^ e) After each calculation is complete within the internal loop, it calls worker->ReportProgress(result) function. In the BGWorker->ProgressChanged() function a separate function, upDataUI(int) draws the result on the main form.
Thanks again for the help.