Re^6: fall through switch/case in perl

Hmm. I think what your saying is that the eval is necessary to avoid a warning if $var doesn't contain a value for which there is a label defined?

No, I'm saying that goto $label dies if the label has not been defined. That is not how it works in C. In C, if you have not provided a case that matches your switch value, it jumps to the default case. That's why there's an eval, to prevent the die (not warning).

[sstone@granite sstone]$ perl -le 'print 1; goto "FOO"; print 2'
1
Can't find label FOO at -e line 1.
[sstone@granite sstone]$
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As far as preventing a warning on undef, well... I'd imagine that that should fit into whatever scheme you are using around undefs: warn if you have undef warnings on, else not. And there's nothing about stringifying $var that changes that semantic, so all seems well and good with my method.

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Re^7: fall through switch/case in perl by BrowserUk (Patriarch) on Sep 07, 2004 at 05:57 UTC
Fair enough, but in TimToady's original, he had `'CASE'.($var+0)` which avoids dieing. `P:\test>perl -le" print 1; $var = 'foo'; goto 'CASE'.($var+0); CASE0: +print 2;" 1 2` [download] And that allows `CASE0:` to become the default. The only situation this doesn't cover is when $var is undef'd; but then none of the other solutions handle that (except the `do{ local $^W; $var + 0 };` I suggested). Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "Think for yourself!" - Abigail "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon	[reply] [d/l] [select]
Re^8: fall through switch/case in perl by etcshadow (Priest) on Sep 07, 2004 at 06:34 UTC
Yes, but what if $var were 11? (Insert Spinal-Tap joke here). Also, as I said: when it comes to the behavior of undef (as the value of $var), shouldn't the surrounding scope's notion of whether or not to warn on undef apply here? Why should this be different (in that specific regard: i.e., whether or not to warn on using an undefined value) than, say, `$var == 10` (etetera). I would think that if warnings were on, it SHOULD warn, and if warnings were not on, then it should NOT warn... and that's what you get. The presence of an eval doesn't change that fact. I'm confused... are we arguing or agreeing? :-D `------------ :Wq Not an editor command: Wq` [download]	[reply] [d/l] [select]
Re^9: fall through switch/case in perl by BrowserUk (Patriarch) on Sep 07, 2004 at 06:53 UTC
I'm confused... are we arguing or agreeing? :-D Agreeing--with gusto :). Yes, but what if $var were 11? Ah! I (stupidly) didn't test that one. Point made. (Insert Spinal-Tap joke here). Actually, if you're so tough that you can make light of a spinal tap, I think I'm gonna agree with you--whatever you say :). Examine what is said, not who speaks. "Efficiency is intelligent laziness." -David Dunham "Think for yourself!" - Abigail "Memory, processor, disk in that order on the hardware side. Algorithm, algorithm, algorithm on the code side." - tachyon	[reply]
Re^10: fall through switch/case in perl by etcshadow (Priest) on Sep 07, 2004 at 19:11 UTC
Re^11: fall through switch/case in perl by BrowserUk (Patriarch) on Sep 07, 2004 at 19:22 UTC
Some notes below your chosen depth have not been shown here
Re^7: ** fall through switch/case in perl by Anonymous Monk on Sep 07, 2004 at 08:43 UTC
`goto qw [CASE1 CASE2 CASE3 CASE4 CASE5 CASE6 CASE7 CASE8 CASE9 CASE10] [$var - 1] \|\| "default"; CASE10: print "a"; CASE9: print "b"; CASE8: print "c"; CASE7: print "d"; CASE6: print "e"; CASE5: print "f"; CASE4: print "g"; CASE3: print "h"; CASE2: print "i"; CASE1: print "j"; print "\n"; default:` [download]	[reply] [d/l]
Re^8: ** fall through switch/case in perl by Beechbone (Friar) on Sep 08, 2004 at 13:59 UTC
You missed the $var=undef and $var<=0 cases. `goto (undef, 'CASE01' .. 'CASE10')[abs($var) == $var ? $var+0 : 0]\|\|"d +efault"; CASE10: print "a"; CASE09: print "b"; CASE08: print "c"; CASE07: print "d"; CASE06: print "e"; CASE05: print "f"; CASE04: print "g"; CASE03: print "h"; CASE02: print "i"; CASE01: print "j"; print "\n"; default:` [download] _Search, Ask, ^Know	[reply] [d/l]