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Re^7: substr oddity

by BrowserUk (Pope)
on Mar 04, 2005 at 23:55 UTC ( #436812=note: print w/replies, xml ) Need Help??


in reply to Re^6: substr oddity
in thread Perl oddities

Right! Before we get into a harranging match, I don't think that you studied the program output from my last post properly. If you did, then we are simply agreeing, but do not know it yet :).

The point I was making, was that on Win32, I never get any indication that your snippet crashes on my machine. Nothing. Zip. Nada. Not a jot:)

  • Nothing in the system or application event logs that always log if an program segfaults or otherwise terminates abnormally.
  • Nothing on the terminal that indicates anything is at fault--except the complete absence of your "Alive!" message. (which is something, but only in the "it didn't happen" way, and could not be classed as "a crash!".
  • No Dr. Watson, or system pop-up telling me that perl crashed in some way.

    So, by your description of "crash", I assumed you were getting some indication on your system that Perl had crashed--such as the "core dumped" message.

    If you are not getting this message, then your characterisation of this as a "crash" maybe accurate, in as much as Perl is certainly taking an abnormal path to completetion, but I usually associate the term "crash" with something the OS becomes aware of and reports, rather than (as now seems a possible interpretation of your use of that term) an internal to perl, "bottle out of here cos we're confused and don't bother telling the user anything" behaviour that I am seeing.

    To put that more clearly, calling substr in a lvalue context, with parameters that lie entirely outside the target string, causes a fatal-but-silent termination of the Perl process.

    If this is the behaviour that you are seeing under HP/UX, then I agree it is most definitely worthy of the term "Perl oddity", and I apologies for my having misunderstood you.

    It does not however, cause what I would term a "crash", at least on my system. :)

    So, are we agreeing; disagreeing; agreeing to disagree or disagreeing to agree?

    I'd like to achieve the former but I would settle for the second to last, but I think I have acquired a reputation for tending to the latter--though, of course, I disagree with that assessment :)


    Examine what is said, not who speaks.
    Silence betokens consent.
    Love the truth but pardon error.
  • Replies are listed 'Best First'.
    Re^8: substr oddity
    by Ytrew (Pilgrim) on Mar 07, 2005 at 02:39 UTC
      So, by your description of "crash", I assumed you were getting some indication on your system that Perl had crashed--such as the "core dumped" message.

      *sigh* I'm sorry. No, that's not at all the case, and I agree that I probably mis-used the term 'crash'. I was trying very hard to remember not to say "die" to mean abnormal termination, because the behaviour wasn't a due to the die() command at all.

      To put that more clearly, calling substr in a lvalue context, with parameters that lie entirely outside the target string, causes a fatal-but-silent termination of the Perl process.

      Yes, that's exactly what I get! Again, my use of the term "crash" was probably misleading. I apologize: it seems we've been talking at cross-purposes for a while now. :-(

      So, are we agreeing; disagreeing; agreeing to disagree or disagreeing to agree?

      Well, I think we get the same output, and I think we both agree that it's odd. That counts as agreeing to me. :-)
      --
      Ytrew

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