Difference between revisions of "ON ERROR"

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==See Also==
 
==See Also==
[[DOSERROR()]], [[DISPLAY CALLS]], [[ERRNO()]], [[ERROR()]], [[LIST CALLS]], [[MESSAGE()]], [[ON ESCAPE]], [[ON KEY]], [[PROCLINE()]], [[PROCNAME()]], [[RETRY]], [[SET ONERROR]], [[STRERROR()]]
+
[[ASTACKTRACE()]], [[BEGIN SEQUENCE]], [[DEBUGOUT]], [[DISPLAY CALLS]], [[DOSERROR()]], [[ERRNO()]], [[ERROR()]], [[LIST CALLS]], [[MESSAGE()]], [[PROCLINE()]], [[PROCNAME()]], [[RETRY]], [[SET DEBUGOUT]], [[SET EVENTTRACKING]], [[SET ONERROR]], [[STRERROR()]]
  
 
==Description==
 
==Description==
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procedure badfile
 
procedure badfile
 
   on error
 
   on error
   set message to "File does not exist."
+
   messagebox("File does not exist.")
 
return to master
 
return to master
  
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[[Category:Documentation]]
 
[[Category:Documentation]]
 
[[Category:Commands]]
 
[[Category:Commands]]
[Category:Error Handling]]
+
[[Category:Error Handling]]

Latest revision as of 09:23, 11 October 2016

Purpose

Trap program errors

Syntax

ON ERROR [<command>]

See Also

ASTACKTRACE(), BEGIN SEQUENCE, DEBUGOUT, DISPLAY CALLS, DOSERROR(), ERRNO(), ERROR(), LIST CALLS, MESSAGE(), PROCLINE(), PROCNAME(), RETRY, SET DEBUGOUT, SET EVENTTRACKING, SET ONERROR, STRERROR()

Description

The ON ERROR command causes the specified <command> to be executed if an error is encountered in a program. If ON ERROR is specified without a <command>, then the default Lianja behavior will be restored.

<command>

The <command> can be any Lianja command. After an error is encountered, the ERROR() function will return the error number, and the MESSAGE() function will return the error message. Specifying an '*' as the command causes any errors to be ignored, so should be used with caution.

Example

procedure badfile
  on error
  messagebox("File does not exist.")
return to master
 
on error do badfile
use patrons