Front page | perl.perl5.porters |
Postings from May 2013
On 1 May 2013 16:46, Nicholas Clark <nick@ccl4.org> wrote:
> On Wed, May 01, 2013 at 04:32:07PM +0200, demerphq wrote:
>> It used to be nice and safe to do this:
>>
>> print unpack("H*", $_),"\n"; # lets see what the string looks like in the raw.
>>
>>
>> This is no longer an effective debugging technique. It will NOT tell
>> you what your string looks like. It takes a "daddy knows best"
>> attitude and tries to do the right thing depending on whether the data
>> is utf8 or the data is not. Which means that this:
>>
>> perl -le'unpack "H*", "\x{DF}\x{100}"'
>>
>> Produces completely different results depending on which Perl you are
>> on. On older perls it produces a relatively useful:
>>
>> c39fc480
>
> Add U0:
>
> $ ./perl -le'print unpack "U0H*", "\x{DF}\x{100}"'
> c39fc480
>
> $ perl5.8.9 -le'print unpack "U0H*", "\x{DF}\x{100}"'
> c39fc480
Ah thanks. That fixes the hex part. Trying it on the "v/a" part
produces a corrupted utf8-on string:
$ perl -MDevel::Peek -wle'my $a= "a" x 129; utf8::upgrade($a); print(
my $msg= pack("U0v/a*", $a)); Dump($msg);' | hexdump -C
Wide character in print at -e line 1.
SV = PV(0x5f75150) at 0x5f8b3f0
REFCNT = 1
FLAGS = (PADMY,POK,pPOK,UTF8)
PV = 0x5f9b940
"\201\0aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"\0Malformed
UTF-8 character (unexpected continuation byte 0x81, with no preceding
start byte) in subroutine entry at -e line 1.
[UTF8 "\x{0}\x{0}aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"]
CUR = 131
LEN = 136
00000000 81 00 61 61 61 61 61 61 61 61 61 61 61 61 61 61 |..aaaaaaaaaaaaaa|
00000010 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 |aaaaaaaaaaaaaaaa|
*
00000080 61 61 61 0a |aaa.|
00000084
Trying it with "U0v/U0a" silences the warning, but produces incorrect
(and arguably broken) output:
$ perl -MDevel::Peek -wle'my $a= "a" x 129; utf8::upgrade($a); print(
my $msg= pack("U0v/U0a*", $a)); Dump($msg);' | hexdump -C
SV = PV(0xd45f1d0) at 0xd475410
REFCNT = 1
FLAGS = (PADMY,POK,pPOK,UTF8)
PV = 0xd485960
"\0\0aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"\0
[UTF8 "\x{0}\x{0}aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"]
CUR = 131
LEN = 136
00000000 00 00 61 61 61 61 61 61 61 61 61 61 61 61 61 61 |..aaaaaaaaaaaaaa|
00000010 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 61 |aaaaaaaaaaaaaaaa|
*
00000080 61 61 61 0a |aaa.|
00000084
I don't understand why the string is still utf8-on.
I also dont understand why this new behavior wasn't added by a
regression proof "opt-in" mechanism, instead of with the current
"opt-out" behavior (assuming said behavior wasn't buggy, which it is).
> (apparently today I am supposed to be observing the public holiday. Whether
> I want to or not)
Well thanks for replying! Enjoy your holiday!
cheers,
Yves
--
perl -Mre=debug -e "/just|another|perl|hacker/"
Thread Previous