Foxpro Error Handling
resources Windows Server 2012 resources Programs MSDN subscriptions Overview Benefits Administrators Students Microsoft Imagine Microsoft Student Partners ISV Startups TechRewards Events Community Magazine Forums Blogs Channel 9 Documentation APIs and vfp on error resume next reference Dev centers Retired content Samples We’re sorry. The content you requested vfp on error example has been removed. You’ll be auto redirected in 1 second. Using Visual FoxPro Developing Visual FoxPro Applications Testing structured error handling in c# and Debugging Applications Testing and Debugging Applications Handling Run-Time Errors Handling Run-Time Errors Handling Run-Time Errors Creating Bookmarks and Task List Shortcuts Testing a Project Handling Run-Time Errors Structured Error Handling Debugging Before Bugs Exist Isolating Problems TOC Collapse the table of content Expand the table of content This documentation is archived and is not being maintained. This documentation is archived and is not being maintained. Handling Run-Time Errors Visual Studio .NET 2003 Run-time errors occur after the application starts to execute. Actions that would generate run-time errors include: writing to a file that doesn't exist, attempting to open a table that is already open, trying to select a table that has been closed, encountering a data conflict, dividing a value by zero, and so on. At times, errors occur when users run your application. You can call your own error-handling routine by including ON ERROR. Typically, ON ERROR uses a DO command to run a routine that handles the error, as in: Copy ON ERROR DO My_Error If your application contains no error-handling routines when an error occurs, the application pauses and Visual FoxPro displays an error message with the following options: Cancel If a user chooses Cancel, Visual FoxPro immediately stops running the application and returns control to the system. Ignore If a user chooses Ignore, Visual FoxPro ignores the line that caused the error and continues to the next line in the program. For a complete list and explanation of Visual FoxPro error messages, see Error Messages. Tip Be sure to provide documentation to your users that describes the errors that they might see, and suggests ways in which they can correct e
UsConsultingConsulting HomeServices & TechnologiesVFP ConversionAzure & Other CloudsEnergy SoftwareContact UsStaffingStaffing HomeLooking for Staff?Looking for Work?Contact UsMagazineMagazine HomeAll IssuesSubscribeMy (Digital) MagazinesWhere is my Magazine?My Subscriber AccountAdvertiseWriteFrameworkFramework HomeGet Started & DocumentationDownloadSupport & ServicesTrainingTraining HomeClassesMentoringState of .NETLunch with CODECode CampsASP.NET MVCDevNet TrainingVFP ConversionVFP Conversion HomeServicesToolsArticlesFox End of LifeContact UsSign in! Advertisement: Structured Error Handling in VFP 8 By Markus Egger Download File Tweet Download File Markus Egger Markus is the founder and publisher of CODE Magazine and is EPS President and Chief Software Architect. He is also a Microsoft RD (Regional Director) and the one of the longest (if not THE longest) running Microsoft https://msdn.microsoft.com/en-us/library/aa975615(v=vs.71).aspx MVP (Most Valuable Professional). Markus is also a renowned speaker and author.Markus spends most of his time writing production code. Markus’ client list contains some of the world's largest companies, including many on the Fortune 500. He’s worked as a contractor for Microsoft (including the Visual Studio team) and presented at local user groups and major events, such http://www.codemag.com/article/0301072 as MS TechEd. Markus has been published extensively including MSDN Magazine, Visual Studio Magazine, his own CODE Magazine, and much more. Markus is a supporter of communities in North America, Europe, and beyond.Markus focuses on development in .NET (Windows, Web, Windows Phone, and WinRT) as well as Android and iOS. He is passionate about overall application architecture, SOA, user interfaces, general development productivity, and building maintainable and reusable systems. In his spare time, Markus is an avid windsurfer, scuba diver, ice hockey player, golfer and world traveler. On a rainy day, he is known to enjoy a good game on his PC or Xbox. This article was published in: This article was filed under: Fox to Fox Visual FoxPro Other Languages Advertisement: With the introduction of Visual FoxPro 3.0, error handling in VFP changed substantially.Rather than using "on error" statements, "state of the art" error events became available. Now, 7 years later, more sophisticated error handling mechanisms take center stage as Visual FoxPro 8.0 introduces structured error handling.Handling potential errors in the most gr
gets executed when the corresponding event occurs. Let's examine this in the context of Errors: Error Event: The occurrence of an error. Error Handler: The routine that gets executed when an Error Event occurs. In this context, "routine" covers all of the http://fox.wikis.com/wc.dll?Wiki~ErrorHandler code that is specific to handling the event. It can be a simple command. on error http://www.sweetpotatosoftware.com/spsblog/2008/11/24/ProfessionalErrorHandlingForVFPApplications.aspx quit. In this case, quit is the error handler. Error handlers can make use of other services. The other services are called by the error handler, but are not part of the error handler. on error messagebox( "Error!" ) The messagebox function is not the error handler, just the call and its parameter. Error handlers can have subroutines that are part of error handling the whole error handler. on error do gErrHlr procedure gErrHlr messagebox( "error" ) return The call to gErrHlr and the gErrHlr procedure are the error handler. Error handlers can be built into classes, which take precedence over the on error setting. Define class cFoo as Custom Function error( tnErr, tcMth, tnLin ) Messagebox( "Error!" ) Return Enddefine In this case, cFoo::error is the error handler, which will respond to any Error Event caused by the cFoo class vfp on error or its descendants. VFP provides some functions that are used by error handlers. on error ? message() Is the message function an error handler? Tough call. Ill defer this one to someone else. Following the above logic, the answer is a definitive NO and Yes :-). I believe it's an error handler from VFP's perspective and a called service from the perspective of the error handler in your program.Darrell Greenhouse The default VFP error handler displays a dialog box displaying the error message and gives the user the options of {Cancel, Suspend, Ignore, Help} or {OK, Help} depending on whether the error occurred in a program or interactively. In this case, the error handler is the code contained in VFP. In the following code, an error in the SQLexec function is indicated by a return code less than 0. The code in the IF block executes when there is an error, so it is the error handler. lnResult1 = SQLexec( lnCon, lcSqlCmd ) if lnResult1 < 0 CRLF = CHR(13) + CHR(10) aerror( laErr ) && Data from most recent error lcErrMsg = lcSqlCmd + CRLF for each lxErr in laErr lcErrMsg = lcErrMsg + CRLF + transform( lxErr, "" ) endfor messagebox( lcErrMsg ) _cliptext = lcErrMst && now you can paste it endif -- Carl Karsten 1. A module or object that intercepts errors. (Alternately:) 2. What is sp
not implement error handling in their applications(allowing VFP's default error handler to prevail)or they will display a simple messagebox containing a few pieces of error information such as the values returned from Visual FoxPro's Error(), Message() and Lineno() functions. In either case, this type of error handling is usually woefully inadequate. Not onlyare these approachesof little use to the user, it is probably disconcerting (if not a little frightening) to them. The possible end result of these approaches: bugs go unreported, error information is not captured, and the user's overall confidence in the application is shaken. A Possible Approach to Error HandlingAt Southwest Fox 2008, I presented a session entitled "Creating a Professional VFP Application from Start to Finish" in which I showed the error handler that I use in a number of applications I have developed. That error handler is presented here as one possible approach you can takewhen implementing error handling in your Visual FoxPro applications.There is sure to be room for improvement, but the state informaiton it gathers is pretty extensiveand I've found that most users find the error screen (see screen shots below)to be non-threatening/reassuring when exceptions arise. How to Use the Error HandlerIn order to implement the error handler in your own applications, you'll need the functions and the ON ERROR command thatare in the main.prg of the sample application (provided in the download below). You'll also want to include the issues.scx formin your project and set the MyCompany, MyProduct, MyTechEmailAddress, and MyTechPhoneNumber properties of the issues form with your information. That's about all there is to it. I have included an FLL with the sample, but this is merely used to facilitate the transmittal of the error information via email. If you implement another method of transmission (such as a post to a Web Connection web application), then you needn't include the FLL. To try the error handler out y