in reply to Re^36: Interleaving bytes in a string quickly
in thread Interleaving bytes in a string quickly

unpack 'H' requires bytes. Well, pretty much all of unpack does. That's the point. Just like interleave does.

Note that it properly handles both string formats: 

$ perl -wle'$x="\x80"; for (1..2) { print unpack "H*", $x; utf8::upgra
+de($x); }'
80
80

[download]

It also means that you now have a mechanism that will allow you to construct a string of packed integers that Perl has no way of unambiguously deconstructing.

I don't understand this at all.

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Re^38: Interleaving bytes in a string quickly
by BrowserUk (Patriarch) on Mar 01, 2010 at 21:59 UTC
    It also means that you now have a mechanism that will allow you to construct a string of packed integers that Perl has no way of unambiguously deconstructing.

    I don't understand this at all.

    This is what I mean: 

    $a = ''; $a .= chr 1<<$_ for 0..63;;

Dump $a;;
SV = PVMG(0x37b528) at 0x3058a0
  REFCNT = 1
  FLAGS = (SMG,POK,pPOK,UTF8)
  IV = 0
  NV = 0
  PV = 0x3cb90f8 "\1\2\4\10\20 @\302\200\304\200\310\200\320\200\340\2
+40\200\341\200\200\342\200\200\344
...
\200"\0Malformed UTF-8 character (byte 0xfe) in subroutine entry 
Malformed UTF-8 character (byte 0xfe) in subroutine entry 
Malformed UTF-8 character (byte 0xfe) in subroutine entry 
Malformed UTF-8 character (byte 0xfe) in subroutine entry 
Malformed UTF-8 character (byte 0xfe) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
Malformed UTF-8 character (byte 0xff) in subroutine entry 
 [UTF8 "\x{1}\x{2}\x{4}\x{8}\x{10} 
     @\x{80}\x{100}\x{200}\x{400}\x{800}
     \x{1000}\x{2000}\x{4000}\x{8000}
     \x{10000}\x{20000}\x{40000}
  CUR = 504
  LEN = 512
  MAGIC = 0x3c856c8
    MG_VIRTUAL = &PL_vtbl_utf8
    MG_TYPE = PERL_MAGIC_utf8(w)
    MG_LEN = -1

print join '-', map ord( chop $a ), 1 .. 64;;
0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-
+0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0-0

    [download]

    And: 

    $a = ''; $a .= chr 1<<$_ for 0..63;;

print length $a;;
64

$a = reverse $a;;
Malformed UTF-8 character (byte 0xfe) in reverse at (eval 47)

print length $a;;
75

    [download]

    If Perl can't handle it, it's a bug, not a feature. And not something I would concern myself with trying to handle.

    Yet another, just another red herring.

    Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
    "Science is about questioning the status quo. Questioning authority".
    In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]
[d/l]
[select]

      If Perl can't handle it, it's a bug, not a feature.

      You can't have a bug in a feature without having a feature.

[reply]

        If you regard the fact that you can currently get away with passing silly numbers to chr, as a feature, then every other operation that you can apply to a string, contains a bug. That's lots of bugs.

        At best, you've describe a terminally broken feature. More likely, simply a bug.

        And along the way, wasted a lot of people's time in the process. By drip-feeding obscure hints and innuendos, instead of posting a simple, clear explanation of what you were alluding to.

        Do not bother replying further, because I'm not interested in your games anymore.

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
[reply]

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