a little parsing challenge ☺

Billy Mays noway at nohow.com
Tue Jul 19 04:07:44 CEST 2011


On 7/18/2011 7:56 PM, Steven D'Aprano wrote:
> Billy Mays wrote:
>
>> On 07/17/2011 03:47 AM, Xah Lee wrote:
>>> 2011-07-16
>>
>> I gave it a shot.  It doesn't do any of the Unicode delims, because
>> let's face it, Unicode is for goobers.
>
> Goobers... that would be one of those new-fangled slang terms that the young
> kids today use to mean its opposite, like "bad", "wicked" and "sick",
> correct?
>
> I mention it only because some people might mistakenly interpret your words
> as a childish and feeble insult against the 98% of the world who want or
> need more than the 127 characters of ASCII, rather than understand you
> meant it as a sign of the utmost respect for the richness and diversity of
> human beings and their languages, cultures, maths and sciences.
>
>

TL;DR version: international character sets are a problem, and Unicode 
is not the answer to that problem).

As long as I have used python (which I admit has only been 3 years) 
Unicode has never appeared to be implemented correctly.  I'm probably 
repeating old arguments here, but whatever.

Unicode is a mess.  When someone says ASCII, you know that they can only 
mean characters 0-127.  When someone says Unicode, do the mean real 
Unicode (and is it 2 byte or 4 byte?) or UTF-32 or UTF-16 or UTF-8? 
When using the 'u' datatype with the array module, the docs don't even 
tell you if its 2 bytes wide or 4 bytes.  Which is it?  I'm sure that 
all the of these can be figured out, but the problem is now I have to 
ask every one of these questions whenever I want to use strings.

Secondly, Python doesn't do Unicode exception handling correctly. (but I 
suspect that its a broader problem with languages) A good example of 
this is with UTF-8 where there are invalid code points ( such as 0xC0, 
0xC1, 0xF5, 0xF6, 0xF7, 0xF8, ..., 0xFF, but you already knew that, as 
well as everyone else who wants to use strings for some reason).

When embedding Python in a long running application where user input is 
received, it is very easy to make mistake which bring down the whole 
program.  If any user string isn't properly try/excepted, a user could 
craft a malformed string which a UTF-8 decoder would choke on.  Using 
ASCII (or whatever 8 bit encoding) doesn't have these problems since all 
codepoints are valid.

Another (this must have been a good laugh amongst the UniDevs) 'feature' 
of unicode is the zero width space (UTF-8 code point 0xE2 0x80 0x8B). 
Any string can masquerade as any other string by placing  few of these 
in a string.  Any word filters you might have are now defeated by some 
cheesy Unicode nonsense character.  Can you just just check for these 
characters and strip them out?  Yes.  Should you have to?  I would say no.

Does it get better?  Of course! international character sets used for 
domain name encoding use yet a different scheme (Punycode).  Are the 
following two domain names the same: tést.com , xn--tst-bma.com ?  Who 
knows!

I suppose I can gloss over the pains of using Unicode in C with every 
string needing to be an LPS since 0x00 is now a valid code point in 
UTF-8 (0x0000 for 2 byte Unicode) or suffer the O(n) look up time to do 
strlen or concatenation operations.

Can it get even better?  Yep.  We also now need to have a Byte order 
Mark (BOM) to determine the endianness of our characters.  Are they 
little endian or big endian?  (or perhaps one of the two possible middle 
endian encodings?)  Who knows?  String processing with unicode is 
unpleasant to say the least.  I suppose that's what we get when we 
things are designed by committee.

But Hey!  The great thing about standards is that there are so many to 
choose from.

--
Bill









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