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Re: Javascript to Perl = fail

by JavaFan (Canon)
on May 04, 2012 at 22:36 UTC ( #968999=note: print w/replies, xml ) Need Help??

in reply to Javascript to Perl = fail

sub isprime($) { my $num = $_[1]; $primer = 1; $ValidChars = "2357"; $str = $num; if (index($ValidChars, ord(substr $str, 0, 1)) == 1) { $primer = 0; } return $primer; }
That returns 1 unless the first character of the first argument (assuming you fix the already noticed error regarding $_[1]) equals 3. I think you are calling isprime only with single digit numbers, and want to return if the digit is a prime number. I'd write that as:
sub isprime {$_[0] =~ /^[2357]$/}
although I would fix the name. Or just inline the test -- that's a lot clearer than any name I can think of.
if (($n != 1) && ($n != 0)) { if (isprime($n)) { $prime += $n; } if (!isprime($n)) { $comp += $n; } }
Too many ifs, and too many calls to isprime. I'd write that as:
if ($n =~ /^[2357]$/) { $prime += $n; } elsif ($n !~ /^[01]$/) { $comp += $n; }
Or, when I'm in the mood for something funky, as a ternary returning an lvalue.
That should be spelled length($text).

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[Corion]: (or maybe I just work better from existing code that I munge until it works and I understand it rather than a short abstract text like "implement everything that's needed" ;) )
[ambrus]: Corion: I think in this case you can get away with only a stub for idle, one that always dies when you create it, because AnyEvent::HTTP doesn't use it, not even indirectly through AnyEvent::Handle or AnyEvent::Socket or AnyEvent::DNS.
[Corion]: The "and I understand it" part is optional.
[Corion]: ambrus: Yes but I also need to implement the file / IO watcher, because Prima has that (in Prima::File), and I need to supply the appropriate thing to make push_write etc. work with Prima
[ambrus]: Corion: yes, you need to implement the io watcher, which should be simple because Prima::File is basically that, and the timer watcher form Prima::Timer
[Corion]: ... or so I think. As I said, I'm somewhat vague on how to make AnyEvent cooperate with a callback-driven IO event loop that gives me callbacks when data is available or can be written
[ambrus]: what push_write thing? I don't think you need that. that's implemented generically by AnyEvent::Handle
[Corion]: ambrus: Yeah, that's what I think as well. But you give me an idea, maybe I should start with implementing the timer, as that should be far simpler and with fewer edge-cases/nasty interaction than the file watcher
[ambrus]: You only provide the watcher part that tells when the handle is readable or writable, not the actual writing and reading.
[Corion]: ambrus: Hmmm. It makes sense that AnyEvent would implement the push_write itself, but I think I don't have a good idea of where the boundary between AnyEvent and the underlying event system lies... Implementing the timer should give me a better idea

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