francoiste

ObjEvent (COM error handling) - AutoIt 3.3.14.2

8 posts in this topic

#1 ·  Posted (edited)

i have just upgraded from autoit 3.3.12.0 to 3.3.14.2 and noticed a difference in behaviour.

through WMI i'm querying some system specs of the local environment.

  • with the previous version of autoit i was simply getting an empty string when trying to query a property that is invalid or doesn't exist.
  • with the new version of autoit i'm getting a runtime error and my compiled script terminates.

code snippet:

_MyTest()

Func _MyTest()
    Local $oWMI = ObjGet('winmgmts:\\' & '.' & '\root\cimv2')
    If Not IsObj($oWMI) Then
        MsgBox(48, "WARNING", "Failed to use WMI (winmgmts)!")
        Return
    EndIf

    For $i In $oWMI.ExecQuery('SELECT * FROM Win32_BIOS', 'WQL', 48)
        ;# CAUTION: "$i.Product" throws runtime error after upgrading to AutoIt 3.3.14.2:
        Local $sIdentifier = $i.Manufacturer & "; " & $i.Product & "; " & $i.Version & "; " & $i.SerialNumber

        ConsoleWrite("[Hardware] BIOS fingerprint: " & $sIdentifier & @CRLF)
    Next
    ConsoleWrite("FINISHED." & @CRLF)
EndFunc

i can avoid the termination of my script by adding a custom COM error handler ("ObjEvent") as follows:

_MyTest()

Func _MyTest()
    Local $oErrorHandler = ObjEvent("AutoIt.Error", "_ErrFunc") ;# <--- LOOK HERE

    Local $oWMI = ObjGet('winmgmts:\\' & '.' & '\root\cimv2')
    If Not IsObj($oWMI) Then
        MsgBox(48, "WARNING", "Failed to use WMI (winmgmts)!")
        Return
    EndIf

    For $i In $oWMI.ExecQuery('SELECT * FROM Win32_BIOS', 'WQL', 48)
        ;# CAUTION: "$i.Product" throws runtime error after upgrading to AutoIt 3.3.14.2:
        Local $sIdentifier = $i.Manufacturer & "; " & $i.Product & "; " & $i.Version & "; " & $i.SerialNumber

        ConsoleWrite("[Hardware] BIOS fingerprint: " & $sIdentifier & @CRLF)
    Next
    ConsoleWrite("FINISHED." & @CRLF)
EndFunc

;# Custom COM error handler
Func _ErrFunc($oError)
    Local $sMessage = @ScriptName & " (" & $oError.scriptline & ") : ==> COM Error intercepted !" & @CRLF & _
            @TAB & "err.number is: " & @TAB & @TAB & "0x" & Hex($oError.number) & @CRLF & _
            @TAB & "err.windescription:" & @TAB & $oError.windescription & @CRLF & _
            @TAB & "err.description is: " & @TAB & $oError.description & @CRLF & _
            @TAB & "err.source is: " & @TAB & @TAB & $oError.source & @CRLF & _
            @TAB & "err.helpfile is: " & @TAB & $oError.helpfile & @CRLF & _
            @TAB & "err.helpcontext is: " & @TAB & $oError.helpcontext & @CRLF & _
            @TAB & "err.lastdllerror is: " & @TAB & $oError.lastdllerror & @CRLF & _
            @TAB & "err.scriptline is: " & @TAB & $oError.scriptline & @CRLF & _
            @TAB & "err.retcode is: " & @TAB & "0x" & Hex($oError.retcode) & @CRLF
    ConsoleWrite($sMessage)
    MsgBox(48, "WARNING - COM error", $sMessage)
EndFunc

 

but still i'd be curious to learn the background of the different runtime behaviour with autoit 3.3.14.2

any thoughts?

Edited by francoiste

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#2 ·  Posted (edited)

You must use COM Error Handler

Read in helpfile about 

ObjEvent()

EDIT: as it was change in last AutoIt 3.3.14.x version.

 

mLipok

btw.

Welcome to the forum

 

Edited by mLipok

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And what Error Handler show to you in SciTE console output pane ?


ADO.au3 UDF     POP3.au3 UDF     XML.au3 UDF    How to use IE.au3  UDF with  AutoIt v3.3.14.x  for other useful stuff click the following button:

Spoiler

Last update: 2016-12-23
Any of my own code posted anywhere on the forum is available for use by others without any restriction of any kind. 

My contribution (my own projects): * Debenu Quick PDF Library - UDF * Debenu PDF Viewer SDK - UDF * Acrobat Reader - ActiveX Viewer * UDF for PDFCreator v1.x.x * XZip - UDF * AppCompatFlags UDF * CrowdinAPI UDF * _WinMergeCompare2Files() * _JavaExceptionAdd() * _IsBeta() * Writing DPI Awareness App - workaround * _AutoIt_RequiredVersion() * Chilkatsoft Components * TeamViewer API -UDF * JavaManagement UDF * VIES over SOAPPOP3.au3 UDF *  RTF Printer - UDF * XML.au3 - BETA * ADO.au3 UDF SMTP Mailer UDF * WinSCP UDF *

My contribution to others projects: * _sql.au3 UDF  *

Useful links: * Forum Rules * Forum etiquette *  Forum Information and FAQs * How to post code on the forum * AutoIt Online Documentation * AutoIt Online Beta Documentation * SciTE4AutoIt3 getting started * Convert text blocks to AutoIt code * Games made in Autoit * Programming related sites * Polish AutoIt Tutorial * DllCall Code Generator * 

Wiki: Expand your knowledge - AutoIt Wiki * Collection of User Defined Functions * How to use HelpFile * Best coding practices * 

IE Related:  * How to use IE.au3  UDF with  AutoIt v3.3.14.x * Why isn't Autoit able to click a Javascript Dialog? * Clicking javascript button with no ID * IE document >> save as MHT file * IETab Switcher (by LarsJ ) * HTML Entities *

I encourage you to read: * Global Vars * Best Coding Practices * Please explain code used in Help file for several File functions * OOP-like approach in AutoIt * UDF-Spec Questions *  EXAMPLE: How To Catch ConsoleWrite() output to a file or to CMD *

"Homo sum; humani nil a me alienum puto" - Publius Terentius Afer
"Program are meant to be read by humans and only incidentally for computers and execute" - Donald Knuth, The Art of Computer Programming
:naughty:  :ranting:, be  :) and       \\//_.

Anticipating Errors :  "Any program that accepts data from a user must include code to validate that data before sending it to the data store. You cannot rely on the data store, ...., or even your programming language to notify you of problems. You must check every byte entered by your users, making sure that data is the correct type for its field and that required fields are not empty."

 

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#4 ·  Posted (edited)

are you saying that custom COM error handlers are now "mandatory", as otherwise any script will terminate with error?

can you point to some references, please?
i cannot find anything in the "script breaking changes" section ...

Edited by francoiste

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It's not listed in the help file.

But then, the removal of COM errors being fatal wasn't mentioned either and only lasted a version or 2.


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interesting.

in the changelog i found for version "3.3.10.0"

Run-time errors on objects no longer fatal (execution of the script is not halted)

so it seems this was now rolled-back by version "3.3.14.2"?

conclusion:
from now on i'll put custom COM error handlers all over the place.
because otherwise it breaks my scripts.

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#7 ·  Posted (edited)

Even if there was no obligation to use it, it's good practice is to use it.
It is my experience as a creator of many of the UDF based on ActiveX and COM objects.

 

Edit:
If you want to know why, just answer here to this my question:

And what Error Handler show to you in SciTE console output pane ?

Edited by mLipok

ADO.au3 UDF     POP3.au3 UDF     XML.au3 UDF    How to use IE.au3  UDF with  AutoIt v3.3.14.x  for other useful stuff click the following button:

Spoiler

Last update: 2016-12-23
Any of my own code posted anywhere on the forum is available for use by others without any restriction of any kind. 

My contribution (my own projects): * Debenu Quick PDF Library - UDF * Debenu PDF Viewer SDK - UDF * Acrobat Reader - ActiveX Viewer * UDF for PDFCreator v1.x.x * XZip - UDF * AppCompatFlags UDF * CrowdinAPI UDF * _WinMergeCompare2Files() * _JavaExceptionAdd() * _IsBeta() * Writing DPI Awareness App - workaround * _AutoIt_RequiredVersion() * Chilkatsoft Components * TeamViewer API -UDF * JavaManagement UDF * VIES over SOAPPOP3.au3 UDF *  RTF Printer - UDF * XML.au3 - BETA * ADO.au3 UDF SMTP Mailer UDF * WinSCP UDF *

My contribution to others projects: * _sql.au3 UDF  *

Useful links: * Forum Rules * Forum etiquette *  Forum Information and FAQs * How to post code on the forum * AutoIt Online Documentation * AutoIt Online Beta Documentation * SciTE4AutoIt3 getting started * Convert text blocks to AutoIt code * Games made in Autoit * Programming related sites * Polish AutoIt Tutorial * DllCall Code Generator * 

Wiki: Expand your knowledge - AutoIt Wiki * Collection of User Defined Functions * How to use HelpFile * Best coding practices * 

IE Related:  * How to use IE.au3  UDF with  AutoIt v3.3.14.x * Why isn't Autoit able to click a Javascript Dialog? * Clicking javascript button with no ID * IE document >> save as MHT file * IETab Switcher (by LarsJ ) * HTML Entities *

I encourage you to read: * Global Vars * Best Coding Practices * Please explain code used in Help file for several File functions * OOP-like approach in AutoIt * UDF-Spec Questions *  EXAMPLE: How To Catch ConsoleWrite() output to a file or to CMD *

"Homo sum; humani nil a me alienum puto" - Publius Terentius Afer
"Program are meant to be read by humans and only incidentally for computers and execute" - Donald Knuth, The Art of Computer Programming
:naughty:  :ranting:, be  :) and       \\//_.

Anticipating Errors :  "Any program that accepts data from a user must include code to validate that data before sending it to the data store. You cannot rely on the data store, ...., or even your programming language to notify you of problems. You must check every byte entered by your users, making sure that data is the correct type for its field and that required fields are not empty."

 

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are you saying that custom COM error handlers are now "mandatory", as otherwise any script will terminate with error?

Not quite, the opposite really, COM errors are not fatal in themselves but will obviously affect your script and could cause them to fail.

But yes error handlers must be used by any sane person. In the past AutoIt was handling them when one was not present.

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