Vista - PSH Guru needed ! : Trapping terminating errors

When I try this
trap { "Got it : division by zero !" } 1/$null; "next"

The trap is working successfully :
Got it : division by zero !
Tentative de division par zéro.
Au niveau de ligne : 1 Caractère : 44
+ trap { "Got it : division by zero !" } 1/$ <<<< null; "next"

But when I try this (who's the same thing in theory) :
trap { "Got it : division by zero !" } 1/0; "next"

I got :
Tentative de division par zéro.
Au niveau de ligne : 1 Caractère : 44
+ trap { "Got it : division by zero !" } 1/0 <<<< ; "next"

And my trap is not working !!!

What's wrong !? I have a big headhache with that problem ! Please help me !

Arnaud Petitjean
http://www.powershell-scripting.com
The PowerShell's French Community

1/0 fails at compile time, so nothing is wrong, don't worry

--
Thanks,
Roman Kuzmin
PowerShellFar and FarNET: http://code.google.com/p/farnet/

The trap works when division by a variable which's value is zero.
I'm no guru though

$zero = 0
trap { "Got it : division by zero !" } 1/$zero; "next"

....or in the pipe:
1,6,9,0 | foreach-object {trap { "Got it : division by zero !" } 1/$_ };
"next"

--
Kiron

<PowerShell In Action> metioned this case, I paste the Author note here:

The example here uses 1/$null. The reason for doing this instead of simply
1/0 is because the PowerShell interpreter does something called constant
expression folding. It looks at expressions that contain only constant
values. When it sees one, it evaluates that expression once at compile time
so it doesn¡¯t have to waste time doing it again at runtime. This means that
impossible expressions, such as division by zero, are caught and treated as
parsing errors. Parsing errors can¡¯t be caught and don¡¯t get logged when
they¡¯re entered interactively, so they don¡¯t make for a good example. (If
one
script calls another script and that script has one of these errors, the
calling
script can catch it, but the script being parsed cannot.)

"A. Petitjean" <APetitjean@discussions.microsoft.com>
news:E32C470A-9D56-498C-837B-F15C2A06147B@microsoft.com...
> When I try this
> trap { "Got it : division by zero !" } 1/$null; "next"
>
> The trap is working successfully :
> Got it : division by zero !
> Tentative de division par z¨¦ro.
> Au niveau de ligne : 1 Caract¨¨re : 44
> + trap { "Got it : division by zero !" } 1/$ <<<< null; "next"
>
> But when I try this (who's the same thing in theory) :
> trap { "Got it : division by zero !" } 1/0; "next"
>
> I got :
> Tentative de division par z¨¦ro.
> Au niveau de ligne : 1 Caract¨¨re : 44
> + trap { "Got it : division by zero !" } 1/0 <<<< ; "next"
>
> And my trap is not working !!!
>
> What's wrong !? I have a big headhache with that problem ! Please help me
!
>
> Arnaud Petitjean
> http://www.powershell-scripting.com
> The PowerShell's French Community

Ah Ok, I understand now !
Thanks a lot for your help.

Arnaud

"Edengundam" wrote:

> <PowerShell In Action> metioned this case, I paste the Author note here:
>
> The example here uses 1/$null. The reason for doing this instead of simply
> 1/0 is because the PowerShell interpreter does something called constant
> expression folding. It looks at expressions that contain only constant
> values. When it sees one, it evaluates that expression once at compile time
> so it doesn¡¯t have to waste time doing it again at runtime. This means that
> impossible expressions, such as division by zero, are caught and treated as
> parsing errors. Parsing errors can¡¯t be caught and don¡¯t get logged when
> they¡¯re entered interactively, so they don¡¯t make for a good example. (If
> one
> script calls another script and that script has one of these errors, the
> calling
> script can catch it, but the script being parsed cannot.)
>
> "A. Petitjean" <APetitjean@discussions.microsoft.com>
> news:E32C470A-9D56-498C-837B-F15C2A06147B@microsoft.com...
> > When I try this
> > trap { "Got it : division by zero !" } 1/$null; "next"
> >
> > The trap is working successfully :
> > Got it : division by zero !
> > Tentative de division par z¨¦ro.
> > Au niveau de ligne : 1 Caract¨¨re : 44
> > + trap { "Got it : division by zero !" } 1/$ <<<< null; "next"
> >
> > But when I try this (who's the same thing in theory) :
> > trap { "Got it : division by zero !" } 1/0; "next"
> >
> > I got :
> > Tentative de division par z¨¦ro.
> > Au niveau de ligne : 1 Caract¨¨re : 44
> > + trap { "Got it : division by zero !" } 1/0 <<<< ; "next"
> >
> > And my trap is not working !!!
> >
> > What's wrong !? I have a big headhache with that problem ! Please help me
> !
> >
> > Arnaud Petitjean
> > http://www.powershell-scripting.com
> > The PowerShell's French Community
>
>
>