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RE: RE: Number of times I've used goto in Perl

by btrott (Parson)
on Apr 19, 2000 at 00:54 UTC ( #7973=note: print w/ replies, xml ) Need Help??


in reply to RE: Number of times I've used goto in Perl
in thread Number of times I've used goto in Perl

Actually, if you've ever done much module/OO programming, you've probably used goto quite a lot, particularly if you write AUTOLOAD functions. From perltoot:

When Perl tries to call an undefined function in a particular package and that function is not defined, it looks for a function in that same package called AUTOLOAD. If one exists, it's called with the same arguments as the original function would have had. The fully-qualified name of the function is stored in that package's global variable $AUTOLOAD. Once called, the function can do anything it would like, including defining a new function by the right name, and then doing a really fancy kind of goto right to it, erasing itself from the call stack.
As such goto is used in quite a few modules, core or otherwise. CGI.pm, for example.


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RE: RE: RE: Number of times I've used goto in Perl
by turnstep (Parson) on Apr 19, 2000 at 01:48 UTC
    Ok, perhaps the question should read: "How many times have you inserted the 'goto' keyword into one of your scripts?" CGI.pm and most others simply use the goto as part of the AUTOLOAD feature, so I let them slide....but, glancing through the standard modules, there are some exceptions: sigtrap.pm, autouse.pm, and (oh no!) even good old Carp.pm use 'goto' as a way of reaching another part of their script. Bleh! I'm still at 'never.'
      Point taken. :)

      But in the case of Carp, my Carp.pm uses goto in the same magical way that it's used in AUTOLOAD:

      goto &longmess;
      The purpose being that this magical goto erases the calling function from the call stack, which is exactly why it's used here: since longmess dumps out a stack trace, we don't want shortmess showing up in the call stack.

      So you should let Carp.pm slide, too. :)

      BTW, I like the perlfunc entry for goto:

      goto - create spaghetti code
        OK, I'll let Carp slide as well. :) (Is this thread nested enough yet?)
      Maybe the question should read "what is the most goto's you've used in a single script/program". I answered "more than ten" even though I rarely use goto, just because I've written so many scripts. Adding a goto is usually better than duplicating code and/or re-arranging a large and complex loop.

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