HandleError

HandleError is a member of the APLTree library. The library is a collection of classes etc. that aim to support the Dyalog APL programmer. Search GitHub for "apltree" and you will find solutions to many every-day problems Dyalog APL programmers might have to solve.

Note: HandleError releases are published as Tatin packages, see there.

Overview

HandleError offers a method Process which is useful to handle application errors on a general (or application) level.

It has the following goals:

• Create a namespace crash and populate it with variables providing all sorts of information potentially important for analyzing the error. This namespace is also saved in a component file by default. This is mainly for applications that cannot save an error workspace because threads are used.
• Create an HTML page with essential information regarding the error.
• Attempt to save an error workspace. In order to achieve that all running threads are killed by default; the main thread will always survive anyway, and so will the thread dealing with the error since a thread cannot kill itself. (See killThreads or how to change this default behaviour)

All options can be changed by setting variables in the namespace returned by CreateParms which can be passed as right argument to the main function Process. For defaults just pass an empty vector to Process.

You can make Process execute your own code by setting logFunction and/or customFns.

Examples

This example sets error trapping for an application so that HandleError.Process uses defaults (empty right argument):

      ⎕TRAP←(405 'E' '#.HandleError.Process ⍬')

This is typically done at a very early stage of an application, when we don't know yet where to save stuff etc.

This example uses the internal function SetTrap for setting ⎕TRAP:

      ⎕TRAP←#.HandleError.SetTrap ⍬

#.HandleError.SetTrap checks whether the right argument is empty (early stage) or a parameter space and whether it is running under a development EXE or a runtime EXE and acts accordingly.

This example calls HandleError.CreateParms in order to create a command namespace and then modifies some of them. Note the usage of #.⎕SHADOW in order to make sure that the ⎕TRAP statement can always "see" the right argument: it's kind of a global but at the same time it is local in the sense that it will disappear once the function quits that contains these lines:

      #.⎕SHADOW'HandleErrorParms'
      #.HandleErrorParms←#.HandleError.CreateParms
⍝ The variables and their settings:
 addToMsg              
 checkErrorFolder    1 
 createHTML          1 
 customFns             
 customFnsParent       
 enforceOff          0 
 errorFolder           
 logFunction           
 logFunctionParent     
 off                 1 
 returnCode          1 
 saveCrash           1 
 saveErrorWS         1 
 saveVars            1 
 signal              0 
 trapInternalErrors  1 
 trapSaveWSID        1 
 windowsEventSource    

      ⎕TRAP←(405 'E' '#.HandleError.Process #.HandleErrorParms')

A detailed documentation is available via

]adoc HandleError