Hi,
The other suggestions will probably bring you to realise this, but I
wanted to make it a little more obvious...
When attempting to catch an error and disarm it for your own error handling
scheme you will find that using 'set/any is needed rather than a set-word
for maximum strength error handling. For example:
Use
>> if error set/any fred try [print "done"] [print "Error!"]
done
>>
Rather than
>> if error fred: try [print "done"] [print "Error!"]
All that try does is catches any error that may be encountered and returns
it in as an Error! datatype. 'try doesn't care if a datatype that cannnot
be assigned via 'set or a set-word is passed, it will only attempt to
'disarm an error within the argument passed to it.
HTH
Ammon
----- Original Message -----
From: "Ed Dana" <[EMAIL PROTECTED]>
To: "REBOL List" <[EMAIL PROTECTED]>
Sent: Tuesday, August 27, 2002 7:51 PM
Subject: [REBOL] Help me, Obi Reb Kenobi, you're my only hope!
> OK, so what's going on here.
>
> I'm trying to put a little error handling around my application. If it
> fails, I need it to send out an alarm. But, depending on the statement,
> I get an error when trying to trap the error.
>
> For example, this works as expected:
>
> >> If Error? Fred: Try [ 1 / 0 ] [ Print "Whatever!" ]
> Whatever!
>
> As does this:
>
> >> If Error? Fred: Try [ 1 / 1 ] [ Print "Whatever!" ]
> == none
>
> This too:
>
> >> If Error? Fred: Try [ Print ] [ Print "Whatever!" ]
> Whatever!
>
> But this doesn't:
>
> >> If Error? Fred: Try [ Print "Get a grip!" ] [ Print "Whatever!" ]
> Get a grip!
> ** Script Error: Fred needs a value
> ** Near: If Error? Fred: Try [Print "Get a grip!"]
>
> This is confusing because why should I get an error on something that
> doesn't and shouldn't cause an error.
>
>
> This works, of course:
>
> >> If Error? Fred: Try [ x: 1 ] [ Print "Whatever!" ]
> == none
>
> And this:
>
> >> If Error? Fred: Try [ x: 1 / 0 ] [ Print "Whatever!" ]
> Whatever!
>
> And so do these:
>
> >> If Error? Fred: Try [ Do [ 1 / 0 ] ] [ Print "Whatever!" ]
> Whatever!
>
> >> If Error? Fred: Try [ Do [ 1 / 1 ] ] [ Print "Whatever!" ]
> == none
>
> What's perplexing about the previous two is that it is a "Do" statement
> that I am trying to execute and trap. Instead of functioning as above,
> it blows up and gives me the "needs a value error".
>
> And curiously, not only does Print fail, but so does Write. And that is
> a function that I need error trapping on, if ever there was one.
>
> >> If Error? Fred: Try [ Write %Temp.txt "Yup!" ] [ Print "Whatever!" ]
> ** Script Error: Fred needs a value
> ** Near: If Error? Fred: Try [Write %Temp.txt "Yup!"]
>
> I've even tried disarming the error, but to no avail:
>
> >> If Error? Fred: Try [ Write %Temp.txt "Yup!" ] [ Print "Whatever!" ]
Disarm Fred
> ** Script Error: Fred needs a value
> ** Near: If Error? Fred: Try [Write %Temp.txt "Yup!"]
>
> So what gives? Is this some subtle intricacy of the language, a bug, or my
normal state of confusion?
>
> --
> Sincerely, | Mud can make you prisoner, and the plains can bake
> Ed Dana | you dry. Snow can burn your eyes, but only people
> Software Developer | make you cry.
> 1Ghz Athlon Amiga | -- Lee Marvin, Paint Your Wagon.
> =========== http://OurWorld.CompuServe.com/Homepages/EDanaII ===========
>
>
>
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>
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