| Re: Hoping ON_IOERROR would catch errors in IDLs subroutines. [message #64937] |
Tue, 03 February 2009 19:49 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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M. Katz writes:
> I'm trying to understand why ON_IOERROR doesn't catch an error that
> occurs with writing an image to the disk. Here's an example where I
> attempt to write an image to an intentionally nonexistent folder (see
> below).
>
> When I run the program it breaks at WRITE_PNG instead of jumping down
> to BAD_IO. However, if I change the WRITE_PNG to an OPENW, then it
> catches the error and redirects the flow the BAD_IO.
>
> What is the proper protocol to catch file errors in routines that IDL
> provides, and handle them in the parent procedure?
I pretty much handle everything with CATCH. I've never
had a problem with it.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: Hoping ON_IOERROR would catch errors in IDLs subroutines. [message #64938 is a reply to message #64937] |
Tue, 03 February 2009 15:40  |
Michael Galloy
Messages: 1114
Registered: April 2006
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Senior Member |
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M. Katz wrote:
> I'm trying to understand why ON_IOERROR doesn't catch an error that
> occurs with writing an image to the disk. Here's an example where I
> attempt to write an image to an intentionally nonexistent folder (see
> below).
>
> When I run the program it breaks at WRITE_PNG instead of jumping down
> to BAD_IO. However, if I change the WRITE_PNG to an OPENW, then it
> catches the error and redirects the flow the BAD_IO.
IDL must not be considering errors in WRITE_PNG "IO errors".
> What is the proper protocol to catch file errors in routines that IDL
> provides, and handle them in the parent procedure?
In general, CATCH catches errors in user or system routines. Try:
pro error_test1
catch, error
if (error ne 0L) then begin
catch, /cancel
print, 'i caught the error!'
return
endif
nonexistent_folder = '/pink/elephant/'
write_png, nonexistent_folder+'x.png', [[0b,1b],[1b,0b]]
print, 'All is well.'
end
--
www.michaelgalloy.com
Tech-X Corporation
Associate Research Scientist
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