Error Reporting Perl
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Perl Reporting Framework
Is there somehow I can "turn on" error message/error handling in Perl, putting out error message like Apache do by default with PHP? Explaining which line the error is at. Greetings php perl error-handling share|improve this question asked May 2 '11 at 21:34 Fredrik 20931223 add a comment| 1 Answer 1 active oldest votes up vote 14 down vote accepted Maybe you're after CGI::Carp. This module lets you redirect errors perl crystal reports and/or warnings to the browser window. From the doco: use CGI::Carp qw(fatalsToBrowser); die "Fatal error messages are now sent to browser"; share|improve this answer edited May 2 '11 at 22:15 answered May 2 '11 at 22:00 dwarring 3,03811323 1 Perfect! That was what I was after. –Fredrik May 2 '11 at 22:07 4 Thee's also warningsToBrowser as in: use CGI::Carp qw(fatalsToBrowser warningsToBrowser); –shawnhcorey May 2 '11 at 22:37 5 But only use these in development. Turn them off in production. There's a very good reason why the default Apache approach is to display something vague to the user. It's all about security. –Dave Cross May 3 '11 at 6:06 Don't forget to accept this answer. –Francisco R May 3 '11 at 8:22 add a comment| Your Answer draft saved draft discarded Sign up or log in Sign up using Google Sign up using Facebook Sign up using Email and Password Post as a guest Name Email Post as a guest Name Email discard By posting your answer, you agree to the privacy policy and terms of service. Not the answer you're looking for? Browse other questions tagged php perl error-handling or ask your own question. asked 5 years ago viewed 878 times
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to top • Download PDF Show page index • Show recent pages Home > Core modules ruby reporting (C) > Carp Please note: Many features of this site require JavaScript. You appear to have JavaScript disabled, or are running a non-JavaScript capable web browser. To get http://stackoverflow.com/questions/5862740/enable-error-message-in-perl-like-php the best experience, please enable JavaScript or download a modern web browser such as Internet Explorer 8, Firefox, Safari, or Google Chrome. Recently read Carp NAMESYNOPSISDESCRIPTIONForcing a Stack TraceStack Trace formattingGLOBAL VARIABLES$Carp::MaxEvalLen$Carp::MaxArgLen$Carp::MaxArgNums$Carp::Verbose$Carp::RefArgFormatter@CARP_NOT%Carp::Internal%Carp::CarpInternal$Carp::CarpLevelBUGSSEE ALSOCONTRIBUTINGAUTHORCOPYRIGHTLICENSENAME Carp - alternative warn and die for modules SYNOPSIS use Carp; # warn user (from perspective of caller) carp "string trimmed to 80 http://perldoc.perl.org/Carp.html chars"; # die of errors (from perspective of caller) croak "We're outta here!"; # die of errors with stack backtrace confess "not implemented"; # cluck, longmess and shortmess not exported by default use Carp qw(cluck longmess shortmess); cluck "This is how we got here!"; $long_message = longmess( "message from cluck() or confess()" ); $short_message = shortmess( "message from carp() or croak()" );DESCRIPTION The Carp routines are useful in your own modules because they act like die() or warn(), but with a message which is more likely to be useful to a user of your module. In the case of cluck() and confess() , that context is a summary of every call in the call-stack; longmess() returns the contents of the error message. For a shorter message you can use carp() or croak() which report the error as being from where your module was called. shortme
I: Basic Perl 01-Getting Your Feet Wet 02-Numeric and String Literals 03-Variables 04-Operators 05-Functions 06-Statements 07-Control Statements 08-References Part II: Intermediate Perl 09-Using Files 10-Regular Expressions 11-Creating Reports Part III: Advanced Perl https://affy.blogspot.com/p5be/ch13.htm 12-Using Special Variables 13-Handling Errors and Signals 14-What Are Objects? 15-Perl Modules http://perldesignpatterns.com/?ErrorReporting 16-Debugging Perl 17-Command line Options Part IV: Perl and the Internet 18-Using Internet Protocols ftplib.pl 19-What is CGI? 20-Form Processing 21-Using Perl with Web Servers 22-Internet Resources Appendixes A-Review Questions B-Glossary C-Function List D-The Windows Registry E-What's On the CD? 13 - Handling Errors and Signals error reporting Most of the examples in this book have been ignoring the fact that errors can and probably will occur. An error can occur because the directory you are trying to use does not exist, the disk is full, or any of a thousand other reasons. Quite often, you won't be able to do anything to recover from an error, and your error reporting perl program should exit. However, exiting after displaying a user-friendly error message is much preferable than waiting until the operating system or Perl's own error handling takes over. After looking at errors generated by function calls, we'll look at a way to prevent certain normally fatal activities - like dividing by zero - from stopping the execution of your script; this is by using the eval() function. Then, you'll see what a signal is and how to use the %SIG associative array to create a signal handling function. Checking for ErrorsThere is only one way to check for errors in any programming language. You need to test the return values of the functions that you call. Most functions return zero or false when something goes wrong. So when using a critical function like open() or sysread(), checking the return value helps to ensure that your program will work properly. Perl has two special variables - $? and $! - that help in finding out what happened after an error has occurred. The $? variable holds the status of the last pipe close, b
by name in place of die(): # don't do this sub barf { print "something went wrong!\n", @_; exit 1; } # ... barf("number too large") if($number > $too_large); die() has a useful default behavior that depends on no external modules, but can easily be overriden with a handler to do more complex cleanup, reporting, and so on. If you don't use die(), you can't easily localize which handler is used in a given scope. Every Error, Great And Smallwarn() provides a reasonable default for reporting potential errors. Programs run at the command line get warn() messages sent to stderr. CGI programs get warn() messages sent to the error log, under Apache and thttpd [1]. Using CGI::Carp, warnings are queued up for display in the event of a die(), thus making important debugging information available. Even reasonable defaults aren't always what you want. Without changing your code [2], the behavior of warn() and die() can be changed: # send diagnostic output to the end of a log open my $debug, '>>bouncemail.debug'; $SIG{__WARN__} = sub { print $debug $_, join(" - ", @_); }; $SIG{__DIE__} = sub { print $debug $_, join(" - ", @_); exit 0; }; Some logic will want to handle its own errors - some times a fatal condition in one part of code doesn't really matter a hill of beans on the grand scale of the application. A command line print utility may want to die if the printer is off line [3] - a word processor probably does not want to exit with unsaved changes merely because the document couldn't be printed. So, do this: local $SIG{__DIE__} = sub { # yeah, whatever }; # or... local $SIG{__DIE__} = 'IGNORE'; ...or, do the error processing of your choice. Perhaps set a lexically bound variable flag - see Lexicals Make Sense. eval { } may also be used to trap errors raised with die() and warn(), including errors that Perl throws, such as divide by zero errors. Given a word process that shouldn't exit with unsaved data because an attempt to print fails, this is the sane idiom. Registering a handler can be used in conjunction to provide diagnostics, debugging, feedback, explanation, or so forth, but eval { } should be used to actually trap the error and prevent it from becoming fatal. Report EverythingIn the event of a fatal error, display as much information as possible about the current execution context. # intercept death long enough to scream bloody murder $version = '$Id: ErrorReporting,v 1.