in reply to Re: <rant>CPAN modules failing to check for write errors</rant>
in thread <rant>CPAN modules failing to check for write errors</rant>

No, you have to rely on perl returning errors correctly for failed system calls - unless you've just written some nuclear power station control scripts in perl - in that case let me know which power station it was and I'll remember to stay a few thousand miles away from it ;->

Any, back to the topic in hand - say perldoc -f print: 

print FILEHANDLE LIST
print LIST
print Prints a string or a list of strings. Returns true if successful.
If print returns false, that's good enough for me - the important thing is I know the data wasn't written - I can log $! and try to save the data somewhere else etc.

Camel pg 606 rightly bangs on about always checking failed system calls but it sometimes seems to fall on deaf ears :(

  • Comment on Re: Re: <rant>CPAN modules failing to check for write errors</rant>

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Re: Re: Re: <rant>CPAN modules failing to check for write errors</rant>
by toma (Vicar) on May 31, 2004 at 01:29 UTC
    The nuclear power plant software looks like it is written in VB, but it might be MFC. That, along with Flash and Crystal Reports. I hope you feel confident about that!

    For the necessity of testing, I was thinking of the earlier example of the failover of a full nfs filesystem to a new one. That seems like a fair amount of code, and if I wrote it, I would need to test it.

    For example, I was thinking about writing a little test system to see how a module such as File::Slurp handles a full filesystem. Perhaps I could write something like File::Slurp::Failover, which would do the clever nfs failover trick.

    By the way, File::Slurp has some options for error handling. Perhaps it could be used as an example of a good way to handle I/O errors. Or is there a better example of a module that has good I/O error handling?

    It should work perfectly the first time! - toma
[reply]
      The nuclear power plant software looks like it is written in VB, but it might be MFC. That, along with Flash and Crystal Reports. I hope you feel confident about that!

      BOOM !!!!!!!!!!!!!!!!!

      For the necessity of testing, I was thinking of the earlier example of the failover of a full nfs filesystem to a new one. That seems like a fair amount of code, and if I wrote it, I would need to test it.

      Ah yes - I see what you mean. For really critical things I can't see any way round it - generally I assume that any failure from a print is serious enough to switch fs and log whatever was in $!. As you say, it's vitally important that the error handling code does get run before it goes live :)

      Thanks for the info on File::Slurp - I'll have to check it out. No doubt there are modules with good I/O handling on CPAN but I couldnt tell you off hand - another thing to add to my todo list :)

      So I'm going to go off, do a bit more research, and hopefully come back to the monastery with an article and maybe some code for review. Give me a few days and I'll be back :)

[reply]

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