Dismas has asked for the wisdom of the Perl Monks concerning the following question:

Help me, O wise ones...

I've got a Perl script--converted from one in VBasic, that reads the registry and places its result into a variable passed in as an argument. The function's return is just 0 for success, anything else for failure. Is there *any* way to get my perlish paws on the result? Here's the code: 

#!perl
# The following example reads and displays the value in the DWORD regi
+stry value
# HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl\Aut
+oReboot. 

use Win32::OLE;
use constant HKEY_LOCAL_MACHINE => 0x80000002;

my $dwValue = 42;
$strComputer = '.';
$oReg = Win32::OLE->GetObject('winmgmts:{impersonationLevel=impersonat
+e}!\\\\' .
                              $strComputer .
                              '\\root\\default:StdRegProv');
$strKeyPath = 'SYSTEM\\CurrentControlSet\\Control\\CrashControl';
$strValueName = 'AutoReboot';

$oReg->GetDWORDValue(HKEY_LOCAL_MACHINE, $strKeyPath, $strValueName, $
+dwValue);

print 'AutoReboot' . ' == ' . $dwValue, "\n";

[download]


The output, as might be expected, is:

"AutoReboot == 42"

The vbs script, of course, works just fine, setting $dwValue to 1 (the current value on my PC). Thanks for any insight--especially one that shows the way...

Dismas

Replies are listed 'Best First'.
Re: Value Sought from Subroutine Argument?
by friedo (Prior) on Mar 02, 2005 at 15:23 UTC
    You probably need to pass $dwValue as a reference. Try 

    my $dwValue = 42;
$oReg->GetDWORDValue(HKEY_LOCAL_MACHINE, $strKeyPath, 
$strValueName, \$dwValue);

    [download]
[reply]
[d/l]
      Dear Friedo,

      Nope. No joy. Thanks for the suggestion, I do appreciate you taking the time to answer, but it didn't help.

      Dismas
[reply]
Re: Value Sought from Subroutine Argument?
by dragonchild (Archbishop) on Mar 02, 2005 at 15:43 UTC
    Have you tried assigning the result of GetDWORDValue() to $dwValue? I don't use the Win32 namespace, but that would be something I'd try.

    Being right, does not endow the right to be rude; politeness costs nothing.
    Being unknowing, is not the same as being stupid.
    Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
    Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

[reply]
      Dear Dragonchild,

      If by "result" you mean the value returned, that won't do. The sub returns a 0 for success and an error code for failure.

      Thanks JTS,

      Dismas
[reply]
Re: Value Sought from Subroutine Argument?
by PodMaster (Abbot) on Mar 03, 2005 at 07:54 UTC
    No need to play with OLE when you can use Win32::Registry 
    use strict;
use warnings;

use Win32::Registry;

# The following example reads and displays the value in the DWORD regi
+stry value
# HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\CrashControl\Aut
+oReboot. 

my $CrashControl;
$::HKEY_LOCAL_MACHINE->Open(
    q~SYSTEM\CurrentControlSet\Control\CrashControl~,
    $CrashControl
)
    or die "Can't open CrashControl: $^E";

my ($type, $value);

$CrashControl->QueryValueEx("AutoReboot", $type, $value) or die "No Au
+toReboot: $^E";

print "Here's AutoReboot: $value\n";

    [download]

    MJD says "you can't just make shit up and expect the computer to know what you mean, retardo!"
    I run a Win32 PPM repository for perl 5.6.x and 5.8.x -- I take requests (README).
    ** The third rule of perl club is a statement of fact: pod is sexy.

[reply]
[d/l]
Re: Value Sought from Subroutine Argument?
by ikegami (Patriarch) on Mar 02, 2005 at 18:03 UTC

    This is odd. I wonder how Win32::OLE determines the arguments of the functions. I noticed that MSDN documents the argument as being uint32, not uint32& or uint32*. I wonder if that is related.

    I tried passing a pointer using unpack('I', pack('P', $dwValue)), but it didn't help.

[reply]
[d/l]
[select]

Back to Seekers of Perl Wisdom