Foxpro On Error Example
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Types Of Errors In Foxpro
FoxPro Applications Testing 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
Vfp Exception
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 exception handling in batch file 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 de
program execution resumes on the line immediately following the line that caused the error. However, if the error-handling procedure includes RETRY, the program line that caused the error is executed again. If the command specifies a procedure to execute when an error occurs, you can use ERROR(), MESSAGE(), LINENO(), and PROGRAM() to pass the error number, the error message, the program line number, and the program name to the procedure. This information can be used to correct the cause of the error. Remarks: When an error occurs during program execution, Visual FoxPro executes the command you specify with ON ERROR. Typically, https://msdn.microsoft.com/en-us/library/aa975615(v=vs.71).aspx ON ERROR uses DO to execute an error-handling procedure. Use ON ERROR without a command to restore the default Visual FoxPro error handler. ON ERROR procedures cannot be nested. If ON ERROR is issued within an ON ERROR procedure, the default Visual FoxPro error handler is restored. The last sentence in the above quote (about nested "on error" statements) is untrue, at least in VFP 7. For example, in http://fox.wikis.com/wc.dll?Wiki~OnError VFP 7, the following code works: local sPreviousErrorHandler m.sPreviousErrorHandler=on("error") && Save the previous error handler. on error HandleError(m.sPreviousErrorHandler) && If there's an error, call our local error handler. use nonexistent_table && Trip our local error handler. function HandleError(sPreviousHandler) messagebox("Ouch! Returning to previous error handler.") on error &sPreviousHandler endfunc Notice that the "on error" command inside of the "HandleError" function is nested. Even the following, more obviously nested command works: on error on error return && Don't return on the first error, but do on the second one. When in Development Mode, it's always useful to handle errors differently than in Production Mode. In Production Mode, typically your ON ERROR should trigger modal dialog with the error, a suggestion for resolution or to contact the developer, and an OK button (among others). In Development Mode, your ON ERROR should bomb you back into your development environment, or trigger a different custom dialog which includes, at minimum, ok, cancel, and debug buttons. This allows easy access to the environment for debugging errors. There is a nifty lightweight and functional Error Handler in the Fox Foundation Classes From the Hackers Guide: ON ERROR is the last resort for errors that have stumped the local Error method, or occur in
Join INTELLIGENT WORK FORUMSFOR COMPUTER PROFESSIONALS Log In Come Join Us! Are you aComputer / IT professional?Join Tek-Tips Forums! Talk With Other Members Be Notified Of ResponsesTo Your Posts Keyword Search One-Click Access http://www.tek-tips.com/viewthread.cfm?qid=1644784 To YourFavorite Forums Automated SignaturesOn Your Posts Best Of All, It's Free! Join Us! *Tek-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting Guidelines Promoting, selling, recruiting, coursework and thesis posting is forbidden.Tek-Tips Posting Policies Jobs Jobs from Indeed What: Where: jobs by Link To This Forum! Add Stickiness To Your Site By Linking To This Professionally Managed Technical on error Forum.Just copy and paste the BBCode HTML Markdown MediaWiki reStructuredText code below into your site. Microsoft: Visual FoxPro Forum at Tek-Tips HomeForumsProgrammersDBMS PackagesMicrosoft: Visual FoxPro Forum Advice on error handling thread184-1644784 Forum Search FAQs Links MVPs Advice on error handling Advice on error handling AlastairP (TechnicalUser) (OP) 11 Apr 11 03:52 I am debugging my first app on the server at work.When I get a minor foxpro on error error, TALK activates and I see this on the active form. If I close that from, the talk is then visible on the next form.Is there a way to stop this and reset the talk option? RE: Advice on error handling MikeLewis (Programmer) 11 Apr 11 04:51 Are you saying you want TALK to be active, or that you don't want it?I assume you know that SET TALK ON or OFF controls the setting. And, also, that is it is scoped to the data session. In other words, if each form has its own private data session, you need to SET TALK separately in each form (usually in the Load event).In addition, you can set the form's AllowOutput property to specify whether TALK output goes to the form itself or the main window.If this doesn't answer your question, could you clarify exactly what you want to know.Mike __________________________________Mike Lewis (Edinburgh, Scotland)Visual FoxPro articles, tips, training, consultancy RE: Advice on error handling OlafDoschke (Programmer) 11 Apr 11 05:28 SET TALK ON does not report errors, so I think your mixing several things togther here, AlaistairP.VFP is verbose on command results, eg how many records have been processed. If you turn off
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