very rare python expression

[=?GB2312?B?zPC5zw==?=]

Howdy everyone,

I saw a strange python code in pygame project. What does "while
not(x&528or x in l):" mean? Below code works in python2.5, so "x&528"
is not HTML strings.

# snake.py code:
import pygame as p,random
p.init()
q=p.display
T=16
b=q.set_mode([256]*2).fill
l=[]
d=a=x=1
c=p.event.get
while not(x&528or x in l):
l=l[a!=x:]+[x]
while a&528or a in l:a=random.rand range(512)
b(0)
[b(99,(o%T*T,o/32*T,T,T))for o in l+[a]]
q.flip()
p.time.wait(199 )
for e in c(2):
v=e.key-272
n=((v&2)-1)*[1,32][v<3]
if-n-d and 0<v<5:d=n
c()
x=l[-1]+d


Best regards,

--
ShenLei

[Paul Rubin]

Re: very rare python expression

"ðÏ" <littlesweetmel on@gmail.comwri tes:

I saw a strange python code in pygame project. What does "while
not(x&528or x in l):" mean? Below code works in python2.5, so "x&528"
is not HTML strings.

It parses as "x & 528 or x in l". Looks like it came from

http://www.pygame.org/project/833/

and is an attempt to squash the program to as few bytes as possible.

[Wojtek Walczak]

Re: very rare python expression

Dnia Tue, 12 Aug 2008 16:39:27 +0800, =?GB2312?B?zPC5 zw==?= napisa³(a):

Howdy everyone,
>
I saw a strange python code in pygame project. What does "while
not(x&528or x in l):" mean? Below code works in python2.5, so "x&528"
is not HTML strings.

It looks like a check if 528 flag is set. In this way you can set
more than one flag in signle variable:

>>flag1 = 1
>>flag2 = 2
>>flag3 = 4
>>flag4 = 8
>>flag5 = 10
>>flags_set = flag2 | flag4
>>flags_set & flag1

0

>>flags_set & flag2

2

>>flags_set & flag3

0

>>flags_set & flag4

8

>>flags_set & flag5

0


--
Regards,
Wojtek Walczak,

http://www.stud.umk.pl/~wojtekwa/

[=?GB2312?B?zPC5zw==?=]

Re: very rare python expression

Oh, thank you very much. I did know that python can parse number '528'
and keyword 'or' without separator.

2008/8/12 Paul Rubin <"http://phr.cx"@nospam. invalid>:

"ðÏ" <littlesweetmel on@gmail.comwri tes:

>I saw a strange python code in pygame project. What does "while
>not(x&528or x in l):" mean? Below code works in python2.5, so "x&528"
>is not HTML strings.

>
It parses as "x & 528 or x in l". Looks like it came from
>

http://www.pygame.org/project/833/

>
and is an attempt to squash the program to as few bytes as possible.
--

http://mail.python.org/mailman/listinfo/python-list

>

[Edward A. Falk]

Re: very rare python expression

In article <7xtzdqobsy.fsf @ruckus.brouhah a.com>,
Paul Rubin <http://phr.cx@NOSPAM.i nvalidwrote:

>"ðÏ" <littlesweetmel on@gmail.comwri tes:

>I saw a strange python code in pygame project. What does "while
>not(x&528or x in l):" mean? Below code works in python2.5, so "x&528"
>is not HTML strings.

>
>It parses as "x & 528 or x in l". Looks like it came from
>

http://www.pygame.org/project/833/

>
>and is an attempt to squash the program to as few bytes as possible.

Sheesh. The 80's called; they want their floppy drives back.

Even with the whitespace restored, it's awful style.

--
-Ed Falk, falk@despams.r. us.com

http://thespamdiaries.blogspot.com/

[Fredrik Lundh]

Re: very rare python expression

Edward A. Falk wrote:

>It parses as "x & 528 or x in l". Looks like it came from
>>
> http://www.pygame.org/project/833/
>>
>and is an attempt to squash the program to as few bytes as possible.

>
Sheesh. The 80's called; they want their floppy drives back.
>
Even with the whitespace restored, it's awful style.

complaints about style issues in code intentionally written to be as
short as possible? is this Digg, or what?

</F>